Dr Martin Barry's Researches in Embryology. 39 



tial foundation of the embryo ; but if it be the nucleus of the 

 yelk-cell, its importance ceases with the formation of the 

 yelk-cell, and according to the analogy of most cell-nuclei it 

 must subsequently be either entirely absorbed, or continue 

 for a time without forming any new essential object."* 



My observation that the spermatozoon penetrates into the 

 interior of the ovum, after having been by some neglected 

 and by others denied for about a dozen years, and even as 

 lately as in 1852 being ridiculed by Bischoff as " born of the 

 imagination," has at length been fully confirmed ; and this 

 in two quarters, by inquirers acting quite independently of, and 

 unknown to one another, — in animals, moreover, not far 

 from the lowest in the scale, my own researches having been 

 made at the other end of the animal kingdom in the highest 

 class — Mammalia. One of these confirmations was made in 

 this country by Dr Nelson, the other in Germany by Dr 

 Keber. The researches of the former were on ova of an 

 Entozoon, those of the latter on ova of the fresh-water 

 Mussel. Nelson's paper was published in the Philosophical 

 Transactions for last year ;t that of Keber has been published 

 in a separate form. J It is impossible to read the accounts 

 given by these observers without feeling the fullest confi- 

 dence in their observations, made and repeated as they evi- 

 dently were with care and patience that leave nothing in 

 these respects to be desired. 



It was found by Nelson, that the spermatozoa penetrating 

 each ovum of the Entozoon he examined were in considerable 

 number ; but by Keber, that only a single spermatozoon pene- 

 trated the ovum of the fresh-water Mussel. Nelson is one 

 of those who now find in animals at the other end of the Ani- 

 mal Kingdom what I had shewn in Mammalia, that the ger- 

 minal spot, dividing, furnishes the nuclei of the cells out of 



* " Mikroskopische Untersuchungen uber die Uebereinstimmungen in der 

 Struktur und dem Wachsthum der Thiere und Pflanzen." Berlin, 1838-9. 

 S. 660. 



t " The Reproduction of Ascaris Mystax. Phil. Trans. 1852, Part ii. 



X " T)e Spermatozoorum Introitu in Ovula. " Konigsberg, 1853. (The obser- 

 vations were on Unio and Anodonta, and made in 1852.) 



