Ryder.] llU [May 16, 



been made have failed because of the way in which the fundamental 

 question, sex itself, was ignored. Most of the speculations in relation to 

 sex have been content with determining the effects of self and cross- 

 fertilization, and have accordingly dealt with some of the consequences 

 of already achieved sexuality, but have thrown no light whatever upon 

 the probable origin of sex itself. 



"Without questioning the high value of the results of such experimental 

 investigations, the question of the origin of sex is probably nearly or 

 quite beyond the pale of experimental inquiry, in virtue of the fact that 

 even the lowest organisms in which sexuality is manifested, are already 

 so persistently adapted to a certain habit of life, and are consequently so 

 fixed in organization that experimental investigation looking to a modi- 

 fication of their reproductive processes through artificial interference is 

 quite impossible within the limits of a single life-time devoted to experi- 

 mental research. We shall accordingly have to examine the phenomena 

 of sexuality as we find them, and upon careful analysis and comparison 

 try to reach such conclusions as seem to be warranted by the evidence. 



Since sexuality leads to processes of discontinuous growth in the pro- 

 duction of new beings or offspring, it is of the utmost importance that this 

 very important fact should be kept in mind from the start. That it has 

 a significance there can be no doubt, when considered in connection with 

 the manner in which germs are produced in the various types. The 

 manner in which such discontinuity is effected varies within wide limits 

 and is associated with other preliminary processes, such as the formation 

 of fixed colonies of animal organisms and the multiplication of axes or 

 branches in the vegetable kingdom. One of these two processes is, in 

 fact, usually the prelude to the occurrence of the process of the dehiscence 

 of the definitive sexual elements in a great variety of forms. 



When the one process, namely, that of continuous growth of the parent 

 organism, ceases, the reproductive process seems to recur, so that sexual 

 genesis and growth seem to be opposed to each other, as has often been 

 pointed out. The impossibility of otherwise adding or integrating more 

 tissue through the incorporation of more nutriment to a structure already 

 finished, or fully developed, at least for the time being, leads apparently 

 to the recurrence of sexuality. The expression of sexuality is accordingly 

 largely, if not wholly, dependent upon nutrition, and it is from this fun- 

 damental standpoint that it will be dealt with here. 



It will be equally important to consider the peculiar characteristics of 

 sexual cells. In almost all biological works it is asserted that the germ- 

 cells of multicellular forms are in all respects, at first, morphologically 

 identical with the other undifferentiated cells of the parent body. While 

 this statement is true of the young germ-cells, it is untrue of nearly all 

 mature germ-cells. The latter, in their mature condition, present us with 

 form-elements, either of a size greatly in excess of those of the rest of 

 the body or others which are, invariably within the limits of the animal 

 kingdom at least, smaller than any of the cells of the parent organism. The 



