SOME PROBLEMS OF REPRODUCTION. 601 



consideration of the different relations of the progamic divi- 

 sions in tliese two cases that led me to lay down as an em- 

 bracing" formula the statement that for fusion one at least 

 of the two nuclei must be fresh from division.^ This is 

 not yet, I admit, a full physiological explanation, but it is as near 

 to one as we can at present go. It corresponds to what the 

 physicist calls an " interpolation formula." He finds a series 

 of results which, plotted out, give a curve, and that this curve 

 can be expressed by an algebraical formula which embodies 

 all the results obtained, and probably others to be ascertained 

 by fresh experiment, though it would have been impossible to 

 arrive at such by a priori reasoning. And with such foi-mulge 

 we have often to be content as representing a distinct advance 

 for the time in that systematisatiou of knowledge which we 

 call science. 



An opinion broached in my 1891 paper which met with the 

 greatest opposition, not to say discredit, was that nuclei 

 contained in the same cytoplasmic investment, as, for instance, 

 those of the SaprolegnitB, might fuse, and so effect a truly 

 syngamous process (endokaryogamy). Nowadays the cases 

 of the Basidiomycetes, most Ascomycetes, the Ustilagineee, 

 and the XJredinese are very widely regarded as syngamous. 

 And the conjecture of Boveri that certain cases of apparent 

 parthenogenesis when only one polar body was formed 

 might be truly syngamous, the nucleus of the imperfectly 

 detached second polar body moving back and fusing with that 

 of the oosphere, and so taking the place and the role of a 

 sperm, has been brilliantly confirmed by Brauer who has 

 followed up the details in the brine-shrimp Artemia. As 

 we have seen, the second polar body is undoubtedly morpho- 

 logically an oosphere, and can in some cases be " fertilised " 

 (sit venia verbo) by a sperm. This favours Maupas's view 

 that in the actual process of syngamy there is neither "male" 

 nor " female," but that sex is a mere adaptation of the cytoplasm 



' In mauy Coccidiacese a partial disruption of the nucleus of the " egi;," 

 and the expulsion of its frajjinenls, replaces the uiicquil fission with the 

 formation of functional oospliere and rudimentary polar body. 



VOL. 47, I'AKT 4. NEW SKllIES. Q Q 



