Scientific Intelligence — Zoology. 195 



quite sure,' continues the writer, ' that Professor Milne Edwards 

 could not have been aware that he had been completely anticipated 

 in this doctrine by Dr Martin Barry ; or, with his accustomed can- 

 dour, he would have alluded to the circumstances. Dr Barry's views, 

 contained in two papers in Professor Jamesons Edinburgh New 

 Philosophical Journal for January and April 1837, are most clearly 

 expressed. ***** In the Brst of these 



papei-s, he works out the important principle of Von Baer, — that ' a 

 heteroo-eneous or special structure can only arise out of one more 

 homogeneous or general, and this by a gradual change ;' and applies 

 this to the difFerent directions of development, which present them- 

 selves in the primary subdivisions of the animal kingdom at a very 

 early period of the history of the embryo, pointing out at the same 

 time (as M. Milne Edwards has subsequently done) that this fact 

 completely negatives the idea that the vertebrated animal ever passes 

 throuoh the conditions which are characteristic of the radiated, the 

 molluscous, or the articulated. He further shews that the order in 

 which the distinctive characters of the germ are evolved, is that of 

 their generality in the animal kingdom. ' Thus, in development, 

 the structure characteristic of the vertcbrata only cannot manifest 

 itself until there has been assumed essentially a structure common 

 to animals, of which the vertebrata are but a part, and to whose type 

 the type of the vertebrata is subordinate. In like manner, structures 

 subordinate to the type of the vertebrata cannot manifest themselves, 

 until after a modified appearance of the general type, of which they 

 are but partial metamorphoses. More and more special forms are 

 thus reached in succession, until the one most special is at length 

 attained.' In his second paper, he expresses this view still more 

 clearly, in the following table of the history of development of any 

 single organism : — 



1. No appreciahU difference in the germs of all animals (fundamental 



unity). 



2. The class manifest, but the utxler not distinguishable. 



3. The order manifest, but not the family. 



4. The family manifest, but the genus not known. 



5. The genus obvious, but not the species. 



6. The species manifest, but the variety unpronounced. 



7. The variety obvious, but the sexual difference scarcely apparent. 



8. The sexual character obvious, hntthe individual chavactei dbscave. 



9. The individual character in its most special form. 



" In both papers Dr Barry continually puts forth this principle as 

 the groundwork of classification. Thus he says : ' The only sure basis 

 for classification is — not structure, as met with in the perfect state, 

 when function tends to embarrass, but — the history of the develop- 

 ment, at that period when structure presents itself alone.' And 

 again : the fact is, that naturalists have begun just where they should 

 have ended. They have attended to details, but neglected general 



