212 Dr Martin Barry on the 



reappearance does, in the assemblage and metamorphoses of 

 the cells. 



It having been in the germinal spot of the ovum, the most 

 important of all nuclei, that I first saw the remarkable pro- 

 cess above described, and illustrated in figs. 8 to 15, I may 

 hereafter refer to the changes the nucleus undergoes, by tlic 

 expression, germinal spot process. Eut after that process had 

 been seen, and for a long period minutely traced, it vv^as im- 

 possible to prosecute researches on the ovum, without dis 

 cerning more or less of it in the nuclei of various cells. I 

 recognised it in every nucleus seen to descend from the ger- 

 minal spot, and subsequently saw it in bodies which, not only 

 in the embryo, but at all periods of life, have apparently de- 

 scended from that spot — the corpuscles of the blood ; giving, 

 in proof of this, hundreds of drawings in my memoirs. And 

 having seen it also in pus and mucus globules, and epithelium 

 cells, as well as in the elements of all the tissues examined, 

 including those of nearly every tissue in the body, I concluded 

 the process in question to be universal ; and have never since 

 met with a cell, the interior of which led me, for a moment, 

 to doubt the correctness of that conclusion. 



Figs. 22, 23, 24, 25, representing Fig. 22. Pig. 24. 

 blood-cells of the Sparrow and foetal Ox, _ 

 afford examples of the result also of the [ (V\ ^^'"^ 

 process in question being the same as \^ ^vp;;^/ 

 in the ovum ; the cell in fig. 25 being 

 about to produce twin-cells. The pro- 

 cess, however, may lead to a very dif- 

 ferent result. Thus, in Plate I., fig. 36, 

 /5, there are seen escaping, from a parent- Fig. 23. Fig. 25. 

 cell, many cytoblasts* 



* The cytoblasts at /3 in this figure are blood-discs of the foetal Sheep. It will 

 be seen that they arc not round, like the blood-discs usually circulating in the 

 Mammalia, but elliptical. The fact is tliat they are young ])lood-discs, having 

 the same form as that which, according to my observations, is the first form of 

 blood-discs in all animals. I saw it to be so at least in animals at both ends 

 of the t:cale, including Man. I have given drawings of tlieso blood-discs from 

 the Tadpole, fig. 05, and Leech, iig. 3ti a. There is a form, however, anterior 



