Scientific Intelligence »''^Fhy Biology and Zoology, 421 



of organisms there is a common principle of development/'— tho 

 elementary parts of tissues having a like origin in cells, however 

 different the functions of those tissues. The facts made known in 

 the present memoir, not only afford evidence of the justness of tl e 

 views of Schwann, but they farther shew that objects, such as the 

 corpuscles of the blood, having all the same appearance, enter im- 

 mediately into the formation of tissues which physiologically are ex- 

 tremely different. Some of these corpuscles arrange themselves into 

 muscle, and others become metamorphosed into constituent pai*ts 

 of the chorion. But the author thinks it is not more difficult to 

 conceive corpuscles having the same colour, form, and general ap- 

 pearance, undergoing transformations for very different purposes, 

 than to admit the fact made known by two of his preceding memoirs, 

 — namely, that the nucleus of a coll, having a central situation in 

 the group which constitutes the germ, is developed into the whole 

 embryo, while the nuclei of cells occupying less central situations in 

 the group, form no more than a minute portion of the amnion. It 

 is known that in the bee-hive a grub is taken — for a special purpose 

 — from among those born as workers, which it perfectly resembles 

 until nourished with peculiar food, when its development takes a 

 different course from that of every other individual in the hive. — 

 Proceedings of the Royal Society of London. 



20. Researches in Embryology. Third Series. — Additional Ob- 

 sanations. By Dr Martin Barry. — Having, in the paper to which 

 the present is supplementary, made known the fact that the germinal 

 spot in the mammiferous ovum resolves itself into cells, with which 

 the germinal vesicle becomes filled, the author has since directed his 

 attention to the corresponding parts in the ova of birds, batrachian 

 reptiles, and osseous fishes, which he finds to be the seat of precisely 

 the same changes. The numerous spots in the germinal vesicle of 

 batrachian reptiles and osseous fishes are no other than the nuclei of 

 cells. The cells themselves, from their transparency, are at first not 

 easily discerned, and appear to have hitherto escaped notice ; but after 

 tho observer has become aware of their presence, they are, in many 

 instances, seen to be arranged in the same manner, and to present 

 the same interior themselves as the corresponding cells in the ovum 

 of mammalia. In the representations given by Professor Rudolph 

 Wagner, the discoverer of the germinal spot, the author recognises 

 evidence of the same changes in ova throughout the animal kingdom. 

 He confirms and explains the observations of R. Wagner, that in thv 

 ova of certain animals an originally single spot divides into many, 

 and that in the ova of other animals the number of spots increases 

 as the ovum ripens. But he expresses also the opinion, that in all 

 ova there is originally but a single spot, this being the nucleus of the 

 germinal vesicle or cell. The analogy between the ova of mammalia 

 and the animal above mentioned, extends also to the subatince Rur- 

 rounding the germinal vesicle, which consistw of nucleated cuUt>. 



21, Form of the Bhod^particles of the Om\thorht/n<:hus hystrUt 



