Somatic and Germinal Variations Before leaving the subject of variation it is necessary to notice the distinction, which Weismann was the first to emphasise, between somatic and germinal variations.
Somatic Variations Even though acquired characters or variations are not inherited, it does not follow that they do not play an important part in evolution.
Thus, as regards its chances of survival, it matters not whether its whiteness be the result of germinal or somatic variation.
Many birds when kept in captivity lose some of the beauty of their plumage, and this is usually attributed to the sexual organs becoming impaired and reacting on the somatic tissue.
It is scarcely ever possible to say of any particular variation that it is a germinal or a somatic one, because even before birth a developing organism has been subjected to environmental influences.
If it is able to react, it matters not, so far as the chances of survival of the organism are concerned, whether the adaptation is the result of a congenital variation or a somatic one.
Phenomena such as these seem to suggest that in some cases the bright colours of the male may be pathological, that the hormones which the male sexual cells secrete may exercise an injurious effect on the somatic or body tissues.
Some somatic variations are due to the direct action of the environment; they are merely the expression of the manner in which an organism responds to external stimuli.
The former differences are the result of what we may call germinal variations, and the latter the result of somatic variations.
One thing is certain, and that is that acquired characters are not commonly inherited in those organisms in which there is a sharp distinction between the germinal and the somatic cells.
One of the most marked of these secretions consists of a coloured granular matter; which is contained at first in the interior of certain spherical cells, and may afterwards become discharged into the somatic fluid.
The somaticor historical sense is in every case the first that must be ascertained.
Both the somatic and the splanchnic leaf of the mesoderm consist at first solely of a layer of flattened epithelial cells, the mesothelium.
In the dorsal median line both somatic and splanchnic mesoderm become continuous with each other and with the axial mesoderm (Fig.
The second chief function of the splanchnic and somatic mesoderm is the production of the serous membrane investing the body cavity and its contents from the mesothelium lining the primitive coelom.
We can now distinguish the serous lining membrane of the abdominal cavity, derived from the mesothelium of the splanchnic and somatic mesoderm as the peritoneum.
It is not only conceivable that particles might proceed from the somaticto the reproductive cells, but the very nutrition of the latter at the expense of the former is a demonstration that such a passage actually takes place.
They all show the same lacunæ, inequalities, and malformations in intellectual capacity, the same psychic and somatic stigmata.
The section is intended to shew the gradual conversion of the cells of the somatic layer of muscle-plates into muscles.
It shews the general features of the layers during the stage, more especially the differentiation of somatic and splanchnic layers of the mesoblast.
The sex glands are especially important as endocrine organs; in fact the somatic cells are organized around the germ cells, as pointed out above.
Contributions from all lands have conspired to produce this effect, the somatic school of psychologists in Germany having exerted, probably, the most influence.
In the thoracic region the part of the somatic layer in each limb is converted into muscles, which are continued into dorsal and ventral muscles in the thorax (vide fig.
In the appendage-bearing segments the somatic layer is continued up into the appendages.
The heart lies in a space bound below by the splanchnic mesoblast, and to the sides by the somatic mesoblast.
Besides these muscles there are in the thorax, attached to the suctorial extremity of the stomodaeum, three powerful muscles, which I believe to be derived from the somatic mesoblast.
In many of the sections the somatic layer is separated by a considerable interval from the epiblast.
In the intervals between these venous spaces the somatic and splanchnic layers of mesoblast are in contact with each other.
In the parietal region a cavity has now appeared in part of the trunk between the splanchnic and somatic layers of the mesoblast (Plate 36, fig.
This thickening, as is shewn in transverse sections at the stage when the segmental duct becomes separated from the somatic mesoblast (Plate 36, fig.
Very soon, in fact, in an older embryo belonging to this stage, the greater part of the groove becomes segmented off as a duct lying between the epiblast and somatic mesoblast (Plate 36, fig.
Along the line of insertion of each of these septa there is developed a considerable space between the somatic and splanchnic layers of mesoblast.
These cells are not, therefore, derived from prolongations of the somatic and splanchnic layers of the already formed somites, but are new formations derived from the yolk.
The outer or somatic wall becomes very thin indeed, the splanchnic wall, on the other hand, thickens and forms a layer of several rows of elongated cells.
He says with his lips that he loves his fellow men, but there is no accompanying emotional glow, none of the somatic or spiritual accompaniments which are the normal ancillae of love's display.
The tragedy of the play is the permanent mutilation of the wife's hands, the only somatic feature that has "appealed" to the artist.
Few of them bore the somatic signs of intimacy with Mr. Barleycorn.
The body of the embryo is therefore completed; but it still remains connected with its various appendages by a narrowsomatic umbilicus, in which run the stalk of the allantois and the solid cord suspending the yolk-sack.
While the true splanchnic stalk of the yolk-sack is becoming narrow, a somatic stalk connecting the amnion with the walls of the embryo is also formed, and closely envelops the stalk both of the allantois and the yolk-sack.
The mesoblast of the trunk is divided anteriorly into splanchnic and somatic layers.
The ventral part of the outer layer gives rise to the somatic mesoblast, and the dorsal to a section of the voluntary muscular system.
The inner layer of this part forms the splanchnic mesoblast, and the outer layer the somatic mesoblast.
They are at first quite solid and exhibit relatively late a division into splanchnic and somatic layers, between which is placed the primitive body cavity.
The outer or somatic layer of the vertebral plates is formed of a single row of cells, but the inner or splanchnic layer is made up of a kernel of cells on the side of the somatic layer and an inner layer.
The allantois is as before, for the sake of simplicity, omitted; its pedicle would of course lie by the side of ys in the somatic stalk marked by the usual dotted shading.
Each side-plate of mesoblast is divided into a somatic and a splanchnic layer, continuous throughout the vertebral and parietal portions of the plate.
A few dividing male somatic cells were found in the walls of the testis.
As in several of the forms studied, material was collected for examination of the somatic cells, but no favorable cases of mitosis were to be found.
In two new cases the male somatic number and size have been shown to be the same as in the spermatogonia.
Turning now to the female larvae to determine the somatic number, the oogonia proved to be more favorable for counting.
No male somatic cells were found in mitosis, but they would, if found, show the same conditions as in the spermatogonia.
Equatorial plate from somatic tissues of a male pupa, 27 large chromosomes, 1 small one.
Equatorial plate from a somatic cell of a male larva, 23 chromosomes.
This would seem to be a favorable form for determining the chromosome conditions in somatic cells, but no clear equatorial plates were found in either larvae or pupae.
In the somatic cells of the former class he finds in the male the unequal pair, in the female an equal pair, the smaller chromosome being replaced by an equivalent of the larger "idiochromosome.
Abundant material for the study of somaticcells was at hand, but nothing favorable could be found in the sections.
In cases of infantilism the psychical level corresponds more or less intimately to the somatic level, an observation borne out in the case of J.
In the same way, the facts drawn from the somatic and ethnic studies of extinct races are the subject of a separate science--Palethnography, otherwise Prehistory, or Prehistoric Archaeology.
Side by side with them, and among them, are found a number of small tribes more or less uncivilised and animistic, having somatic types of considerable variety.
And in conclusion the castes do not always agree with ethnic and somatic divisions.
Already the distinction between the somatic and the ethnic sciences is embarrassing; thus psychological and linguistic phenomena refer as much to the individual as to societies.
Other somatic traits (projecting nose, lips not thrust out, etc.
The Arab tribes have profoundly modified certain Berber and Ethiopian populations from the somatic point of view as well as the ethnic.
Notwithstanding some local differences, they exhibit great unity, not only from the somatic point of view, but also from the point of view of manners, customs, and speech.
Most of the Guaycurus and their neighbours seem to be of high stature and to have a brownish-yellow skin; but almost nothing is known either as to the shape of their head or their other somatic characters.
It was a gradual process, and therefore the effect of the environment on the germ-cells through the somatic cells continued, though in decreasing degree, and still continues.
In the earliest stages of evolution there was a complete identification of germ-cells and somatic cells--of the individual with the species.
Somatic cells are specially modified for the various functions of the body; germ-cells are wholly unmodified.
The somatic cells are for the conservation of the individual life, the germ-cells for the conservation of the species.
Weismann made many experiments on animals, especially by mutilation, to show that somatic changes are not inherited.
But the differentiation of the germ and somatic cells was not all at once, nor is their sympathetic relation completely severed.
Now, according to Weismann, inheritance is only through germ-cells, while the environment affects only the somatic cells.
The animal body consists of two kinds of cells wholly different in function--somatic cells and germ-cells, including in this last the sexual elements both male and female.
The principal reason of this, as we have already seen, is the increasing differentiation of germ and somatic cells, and the removal of the former to the interior, where they are more and more protected from external influence.
He is a man with a rather unusual clarity of view as to his situation; and his trouble appears to him to be somatic rather than as of the nature of a depression.
The case is placed in the somatic group on account of pulmonary phenomena which it seemed well to relate with those of Case 133.
First it may be well to regard the whole problem in the light of those mental diseases that we slid over when we were delimiting Shell-shock as against syphilis, epilepsy and somatic disease.
Under the war conditions, it might be thought that these somatic disorders yielding the so-called symptomatic mental diseases would be frequently found.
There was no other somatic sign except a pulse of 62.
A somewhat curious somatic complication in a case of Shell-shock hysteria was the finding of a needle in the left upper arm, which was then extracted.
Moore calls attention to somewhat similar phenomena in the somatic group of nervous and depressed cases found in the war.
Here is a case in which, as Nonne states, the somatic trauma required by Oppenheim as the basis of every traumatic neurosis did not occur.
More forcibly than ever is it brought home to us that the constitution of the germ-plasm--not merely the somatic character--is the object of our investigation.
In table 63 is given a list of these different combinations and of the probable associated somatic colors.
Each somatic cell of the hybrid--at least in the comb region--has only half the full determiner for median comb.
Zygotes in F2 of Silkie × Minorca hybrids and their corresponding somatic colors.
The same applies here, if stirring events that occur to the somatic cells can produce any effect at all on offspring.
Moreover, we have seen from the evidence given in my preceding article that the germ-cells issuing from a parent's body can, and do, respond to profound impressions made on the somatic cells.
So by analogy we may explain all somatic and psychic differentiation as functions of the glands of internal secretion.
Any break in thesomatic or psychic equilibrium, a blow or an infection, or a startling thing seen, or a worrisome thought felt, will start a process going.
Without the maternal instinct, without the hope of immortality through somatic or spiritual posterity, we should all, who were sane enough, have to condemn ourselves to the futilities of hedonism.
Or because somatic changes are minor, the psychic will dominate the picture.
Growth, as a general name for the mutations, the ensemble of somatic and psychic differentiation, from year to year, passes through five epochs that are standard for the normal.
Close observation of the correlation of somatic and psychic development in extreme examples of these children corroborates this view.
Long ago, Hippocrates, revered founder of the art of medicine, recognized that there was a specific affinity of disease for individuals with more or less the same characteristic somatic and psychic traits and trends.
Of these twenty-three exhibited the somatic criteria or hormonic signs of the ante-pituitary type.
Adolescence is the period of stress and strain throughout the somatic and psychic organism because of the volcanic upheavals in the sex glands.
The pragmatic test has been and will be the probability that the correction of the somatic or psychic condition would have prevented or will prevent the consent to the crime.
Most characters, somatic or psychic, are the products not of the action of one internal secretion alone, but of the interlinked activities of all of them.
Femininity in a woman, the womanly woman, or the eternal feminine, may indeed be defined by the degree of somatic and psychic exhibitionism she presents.
Many careful observations seem to prove the molecular life of the hair and nails after somatic death.
The walls of the remaining seven somatic cells have not yet formed though the resting or the dividing (M p) nuclei may be seen; c R, chromatin fragments cast off from the somatic cells.
In the few cases where permanent inheritable changes were seemingly produced they were more reasonably interpreted as the effects of direct action on the germ-cells than as examples of inherited somatic modifications.
Only such a condition as this would rank as the inheritance of a somatic modification.
All possess the chromatin or hereditary substance of the organism, though, according to Boveri, the germ cells alone receive all the chromatin of the parent cell, the derived somatic cells having to part with some of it.
