330 / Dr. G. C. Wallich on the lyistinctwe Characters and 



the presence, sometimes of a single, sometimes of multiple en- 

 capsuled nuclei, which I have frequently witnessed, with the 

 occurrence in the same individual of a large number of sarco- 

 blasts of nearly uniform average size, but which size differs very 

 materially from the also uniform size of these multiple nuclei. 

 In short, I believe that whilst duplicative division does take 

 place in the nucleus and the nuclear capsule up to a certain 

 ])oint, it stops there — and that the sarcoblasts are formed within 

 the body of the nucleus, and are not segments of it and its cap- 

 sule combined. This view is strengthened, moreover, by some 

 curious facts which have been observed by me only within the 

 past few days — facts which would seem to indicate that the 

 office of the true nuclei is not identical with that of the sarco- 

 blasts, although in both cases a new brood is the result. How 

 the sarcoblasts escape though the apparently imperforate cap- 

 sule of the nucleus I am ignorant ; but I would remark that in 

 Acanthometra and Thalassicolla they occur within the nuclear 

 body, as well as externally to its capsule (that is to say, 

 throughout the endosarc generally), whereas amongst a multi- 

 tude of the last-named organisms examined by me I have not 

 met with a divided or a dividing nucleus in a single instance ; 

 and in the Foraminifera and Polycystina, which possess no true 

 nucleus at all, the sarcoblasts (" yellow cells'^ of authors) are 

 present in great number. It is possible, however, that I may 

 be in error in regarding my sarcoblasts as identical with the 

 "reproductive cells" of Mr. Carter, more particularly as he de- 

 scribes the latter as invariably exhibiting a distinct capsule in 

 their mature state, whereas I have entirely failed to detect any 

 endogenously formed bodies, besides the nucleus or few multiple 

 nuclei, which possess a definite capsular covering. It only re- 

 mains for me to point out that the sarcoblasts in their early 

 stage present a pale-yellow tint, and are somewhat oily-looking, 

 which is not the case with the multiple nuclear bodies. Addi- 

 tional evidence, however, must be produced before these ques- 

 tions can be regarded as definitively answered. 



Recent examples also enable me to corroborate the statement 

 advanced in my previous papers respecting the occasional occur- 

 rence of a simultaneous tripartite division of the nucleus. When 

 this happens, it is brought about by the inversion of two folds of 

 the nuclear capsule nearly at right angles to each other, one 

 fold passing completely across so as to isolate a segment, whilst 

 the other bisects the remaining portion. In this manner the 

 three divisions, although originally differing in shape, may each 

 contain equal quantities of nuclear matter, and by the gradual 

 rounding of their outline ultimately assume isometrical propor- 

 tions. In these instances, and indeed in the case of the multiple 



