38 Dr Martin Barry's Researches in Embryology. 



to in that dark and previously unexplored period, that I owe 

 my observation of nearly all the facts just mentioned ; and 

 any one of these would have repaid the labour. Had BischofF 

 duly examined the ovum after the coitus and before its ex- 

 pulsion from the ovary, for which nine or ten hours afford 

 ample opportunity, he would have seen it becoming more and 

 more prepared for fecundation, might perhaps have met with 

 it at the very moment of this change, and would at all events 

 have had the opportunity of witnessing the effects thereof in 

 their most incipient stages. He would then have understood 

 the ovum better in the Fallopian tube and uterus, and could 

 not have denied facts which have since established themselves 

 in ova of some of the lower animals, notwithstanding the ob- 

 scuring yelk, and in spite of all the outcry which Bischoff 

 raised against my announcement of them. 



Thus while some laughed at what I maintained regarding 

 the germinal spot, they gave drawings shewing that at the very 

 same time they had divisions and sub-divisions of this myste- 

 rious body before their eyes ; obscured however, in the ova 

 they examined, by a quantity of yelk not present in a solid 

 form, in the mammiferous ovum. Hence the importance of 

 examining the latter at the early period just mentioned. 

 And I now have the satisfaction to see that the illustrious 

 names of Von Baer and Johannes Muller may be added to 

 those who at length find just what I had described as seen in 

 the Mammalia, that the germinal spot, dividing, furnishes the 

 nuclei of the cleft yelk-balls. 



The importance of the nucleus of the cell, the part it takes 

 in producing secondary deposits, and its divisions for the pro- 

 duction of young cells, I believe to be now doubted by very- 

 few of those who have really made adequate inquiry. Yet 

 up to the time when these facts concerning the nucleus were 

 recorded in the Philosophical Transactions, no one had ques- 

 tioned the views of Schleidcn and Schwann, — that after the 

 formation of the cell-membrane the nucleus either " remains 

 unaltered," or " as a useless member is absorbed." Thus 

 Schwann, when discussing the question, whether the germinal 

 vesicle is a young cell, or the nucleus of the yelk-cell, re- 

 marked : " If it be the first, it is very probably the most essen- 



