36 Dr Martin Barry's Researches in Embryology. 



Researches in Embryology ; a Note supplementary to Papers 

 2>ublishcdin the Philosophical Transactions forlSSS, 1839, 

 and 1840, shewing the Confirmation of the Principal Facts 

 there recorded, and pointing out a Correspondence be- 

 tween certain Structures connected with the Mammiferous 

 Ovum and other Ova. By Martin Barry, M.D., F.R.S. 

 F.R.S.E.* (Communicated by the Author.) 



The following are some of the principal facts recorded in 

 my Papers on Embryology : others will be mentioned further 

 on. 



1. The spermatozoon penetrates into the interior of the 

 ovum. 



2. The germinal vesicle persists beyond the period at which 

 it had been supposed to disappear. 



3. Cleavage of the yelk, previously noticed in Batrachian 

 Reptiles, and some Osseous Fishes, takes place in the ovum 

 of the highest animals — Mammalia. 



4. This cleavage of the yelk is effected by means of the 

 nuclei of cells. 



5. The nuclei effecting cleavage of the yelk have their ori- 

 gin in the germinal spot, which divides and subdivides to 

 furnish them. 



6. The nucleus of the cell neither " remains unaltered," nor 

 " is absorbed as useless," after the formation of the cell-mem- 

 brane ; but continues to display properties which shew it to 

 be the most important portion of the cell. 



7. Ova of the Rabbit destined to be developed, are in most 

 instances discharged from the ovary in the course of nine or 

 ten hours post co'itum ; and they are all discharged about the 

 same time. 



Two of these facts, viz., that regarding the period at which 

 the ovum of the Rabbit is usually expelled from the ovary, 

 and the fact that cleavage of the yelk takes place in the marn- 



* The substance of a Paper read before the Royal Society of London, June 

 16, 1853. 



