60 Transactions of the 



weeks, as we shall hereafter see, the only remaining bodies of this 

 kind. What those investigators regarded as a nucleus, by the 

 division of which the process of multiplication is said to take place, 

 I have designated above as an embryo-blood corpuscle. I have 

 preferred this expression because the young blood corpuscle arises 

 not, as is the case in the ordinary endogenous process of multiplica- 

 tion of nuclei and cells, in the form of a globule or vesicle from a 

 liquid protoplasm, but separates, as it appears, directly from the 

 substance of the mother-corpuscle, and possesses from the beginning 

 all the properties of the latter, even that of becoming crenated. 

 In Fig. 2 such a specimen is represented, which, being still enclosed 

 in the mother-substance, already contains an embryo of its own. 



The mode of multiplication of the coloured blood corpuscle of 

 man is, accordingly, one of its own kind, and has, as far as I know, 

 hitherto not been observed. It represents, so to say, the transition 

 from the process of multiplication by endogenous formation, to that 

 of budding, or gemmation. As regards the occurrence of the latter 

 in the tissues of vertebrated animals, I have already observed it, 

 during my researches upon the development of the nervous tissues, 

 to take place in the tissues of older human embryos. I, however, 

 at that time, was not able to understand it in all its bearings, until 

 I observed it again in the membranes of the small ovum above 

 described. Here I had an opportunity to see the whole process 

 going on, affecting the multiplication of the nuclei, as well as that 

 of certain cells arising from a portion of the latter, and destined 

 to the formation of embryonic blood-vessels. The description of 

 this mode of multiplication I must, however, pass over in this 

 place, as it would lead me off too far from my original subject, the 

 origin and development of the blood corpuscles. I shall, therefore, 

 discuss it more minutely in another paper, treating of the formation 

 and development of the embryonic blood-vessels. 



Before pursuing the process of multiplication of the coloured 

 blood corpuscles any farther through the successive stages of 

 embryonic life, we will first examine their origin a little closer. 

 The observations thus far described were made, as already men- 

 tioned, on the fresh specimens examined in the serous liquid of 

 the ovum. At their conclusion, the approaching darkness of the 

 evening interrupted my labours, and it was necessary to put the 

 ovum in a weak solution of chromic acid for preservation. In 

 resuming the investigation on the following day, I examined again 

 a little piece of the balloon-shaped vesicle, but now received another 

 aspect of the object. The canals, namely, had been almost entirely 

 emptied of their blood corpuscles, and were, in consequence, not 

 so easily to be recognized as such, as before. The accumulations 

 of coloured blood corpuscles, however, had, though not in their 

 original bulk, remained behind. Although this circumstance de- 



