Royal Microscopical Society. 49 



So far as I am able to judge from careful examination of these 

 bodies, as well as of others taken from older human embryos, their 

 process of multiplication consists therein, that in the substance of 

 the mother-body, and very near its surface, the separation of a 

 small portion, globular in form, takes place, which represents the 

 embryo-blood corpuscle. Enlarging at the expense of the mother- 

 substance, this makes its way to the surface, and, finally detaching 

 itself, leaves behind a concave depression corresponding to its form. 

 Judging from the number of depressions present on many 

 mother-corpuscles, as well as from the young blood contained 

 within them, this process appeared to have repeated itself from 

 three to four times in the same body. Their reproductive power, 

 however, did not always seem to be in a constant proportion to 

 their size, as, in some instances, the smaller ones showed as many 

 depressions as the larger. This view was confirmed by the fact, 

 that, while many of the larger bodies contained, in addition to the 

 depressions, from three to four embryo-corpuscles, others of the 

 same size gave no evidence either of depressions or blood. In some 

 instances I found three generations represented in one body, the 

 young corpuscle bearing within its substance another embryo- 

 corpuscle, even prior to its own birth. In these cases, however, 

 the mother-corpuscles contained but one or at most two embryo- 

 corpuscles, and only one of these contained the third generation in 

 the form of a small globule. The reproductive force appeared here 

 to have been concentrated at one point. In some cases, where 

 several embryo-corpuscles were contained within one mother-body, 

 they were sometimes situated opposite to each other, having the 

 appearance of having been formed by the division of one body. 

 A change of focus, however, showed this not to be the case. 



As can be seen from the above, the observations thus far 

 described, concerning the process of multiplication of the coloured 

 blood corpuscles, do not correspond to those of other observers. 

 The prevailing theory on this subject is, to the extent of my know- 

 ledge, still that whereby the multiplication takes place by a division 

 of nucleated coloured corpuscles. It rests mainly upon the state- 

 ments of Eemak, Kdlliker, and other investigators, whose obser- 

 vations were made on difi'erent lower and higher vertebrated animals. 

 Whether the process of multiplication of these bodies in the human 

 embryo really differs from that in other vertebrata, or whether this 

 discrepancy is dependent upon other causes, future investigations will 

 decide. 



Those nucleated coloured blood corpuscles which have been 

 noticed by other observers before me to occur up to a certain 

 period of embryonic life, correspond to those mother-blood cor- 

 puscles above described, containing but one embryo-corpuscle. 

 These represent in the blood of the human embryo of six or seven 



