J. Blake— Connection between Isomorphism, ete. 193 
muth has informed me that he has discovered at Burlington a 
series of specimens of intermediate sizes, that show it to be only 
the young or undeveloped condition of one of the large species 
characters of Actinocrinites. This, however, would not neces- 
sarily prove the two types to be generically or subgenerically 
identical, since there are many examples, in various departments 
of natural history, in which two clearly distinct, but allied, 
state, until they advance to a certain stage of growth, which, in 
one, becomes its fixed adult condition; while the other goes on 
collections accumulate; possibly to modify, to some extent, 
the prevalent views in regard to their classification. 
(To be continued.) 
Arr, XXI.—On the Connection between Isomorphism, Molecular 
Weight and Physiological Action; by JAMES BLAKE, M.D. 
which I consider are of interest under a purely chemical point 
of view. In the following table the substances experimente 
with have been arranged in groups according to their physiolog- 
