i5o 



THE EVOLUTION OE SEX. 



for division. In this preparation, according to Boveri, the "muscular fibrils " of 

 a special kind of protoplasm (or archoplasma) literally move the nuclear 

 elements. "The movement of the elements is wholly the result of the contrac- 

 tion of the attached fibrils, and the final arrangement of these nuclear elements 

 in the ' equatorial plate ' is the result of the action of the archoplasmic sphere 

 exerted through the fibrils." Now this specially active protoplasm, which the 

 skillful observer seems to have succeeded in fixing, has its center. There are 

 two central corpuscles, each " ruling a sphere of archoplasms." Where, then, 

 do these centers come from? "It is probable," Boveri says, "that the 

 spermatozoon brings a centrosoma into the ovum, and that this by division 

 forms two centers. Since these two corpuscles condition the division, the 

 dependence of this upon the presence of the spermatozoon is for the Ascaris 

 ovum explained." We have given these details, technical as they are, because 

 they seem to us to show clearly that it is rash to deny that even the minimal 

 cell-substance of the spermatozoon may, as well as its nucleus, have a 

 momentous influence in fertilization. 



III. Physiological Theories of Fertilization. — The morpho- 

 logical facts, established and verifiable by observation, form the basis 

 from which to attack the deeper problem of the physiology of fertili- 

 zation. Here experiment is almost insuperably difficult; only a few 

 incidental results are as yet available; the suggestions thrown out by 

 various naturalists must therefore be appreciated according to their 

 consistence with the general principles of physiology, and with the 

 general theory of sex and reproduction. To some they may still appear 

 a page of probabilities. 



Sachs compares the action of the male element upon the egg-cell 

 to that of a ferment. De Bary also suggests that profound chemical 

 differences exist between the two elements. Very suggestive is the 

 view of Rolph, who regarded the process as essentially one of mutual 

 digestion. His words well deserve quotation: — 



" Conjugation occurs when nutrition is diminished, whether this be due to 

 want of light, or to the lowered temperature of autumn and winter, or to a 

 reduction of the organisms to minimal size. It is a necessity for satisfaction, a 

 gnawing hunger, which drives the animal to engulf its neighbor, to 'isophagy.' 

 The process of conjugation is only a special form of nutrition, which occurs on a 

 reduction of the nutritive income, or an increase of the nutritive needs, in 

 consequence of the above-mentioned conditions. It is an 'isophagy,' which 

 occurs in place of 'heterophagy.' The less nutritive, and therefore smaller, 

 hungrier, and more mobile organism we call the male, — the more nutritive and 

 usually relatively more quiescent organism, the female. Therefore, too, is it 

 that the small starving male seeks out the large well-nourished female for 

 purposes of conjugation, to which the latter, the larger and better nourished it 

 is, is on its own motive less inclined." Cienkowski has also inclined to a 

 similar view, regarding conjugation as equivalent to rapid assimilation. 



Simon also seeks to establish the following among other vague conclusions : 

 Sexuality has, he says, arisen twice (we should say much oftener), once among 

 plants, again among Protozoa. Two similar cells unite " in order to reach the 

 limits of their individuality." In both kingdoms the union is at first protective. 



