276 J. E. S. MOORE. 



produced from one cell, whose residual moiety remains, ac- 

 quiries distinct characters from the rest, and is not converted 

 into the spermatozoa. From such a starting-point we may see 

 our way through a gradual evolution to meet the physiological 

 necessities of the case, to the complex reproductive apparatus 

 in Branchipus, where two different kinds of cells exist in both 

 sexes, one to form the eggs or spermatozoa, and one to form 

 the case or fluid in which these bodies are respectively sus- 

 pended or enclosed. 



Whether akinetic division is really wholly related to the 

 foot-cells in animals is a controverted question, but from what 

 I have seen in Branchipus (figs. 20, 21) and elsewhere, I am 

 inclined to believe that it is not wholly restricted to these ele- 

 ments, but that there is a general tendency towards the two 

 methods in the two kinds of cells. 



To recapitulate, it will be seen then — 



I. That in Branchipus the observations bear out the general 

 law as to the similarity of the male and female cells, and that 

 their own specific peculiarities are physiological in origin, 

 having no morphological significance. 



II. The derivatives of the primitive genital cells (male ova) 

 are of two kinds, one transformed directly into the reproduc- 

 tive elements, the other into the egg- case or into the fluid in 

 which the spermatozoa are suspended. Karyokinesis is the 

 method of procedure in the one — akinesis in the other. 



III. That the divisional phenomena of these cells are inti- 

 mately related to a protoplasmic structure, which might be 

 fitly described as " Schaumplasma," and one of the initial 

 physical impulses towards metamorphosis is a fusion of some 

 of the intra-nuclear globules ; and a considerable portion of the 

 complicated karyokinetic figures, with their centrosomes, pseu- 

 dosomes, and dictyosomes, appear to be the logical as well as 

 the actual consequence of the continuance of this process. 



"With the foregoing results of observation as a basis of com- 

 parison, I made a close examination of the ovigenesis in Apus. 

 Unfortunately the male of this species is practically unknown, 

 ten thousand having been collected without a male appearing 



