CLARK: BATHYMETRICAL DISTRIBUTION OF CRINOIDS 125 



creasing amounts of lactic acid in milk not carefully handled 

 might check the multiphcation of B. abortus. The results showed 

 that lactic acid added to the milk to bring the acidity to 0.4 

 per cent had no effect upon the multiplication of these organisms 

 in the cream layer. 



Bacillus abortus is characteristically an organism infecting 

 cream. Since glycerine has been shown to be one of a very few 

 food substances which it can utilize, and inasmuch as growth takes 

 place slowly, with no apparent effect in litmus milk from which 

 the cream has been removed, but is abundant in the cream layer 

 of whole milk, with the production of acid, the facts suggest that 

 the butter fat is broken down to obtain the glycerine and that 

 the fatty acids thus liberated increase the acidity of the milk. 

 Chemical determinations will be made to prove or disprove this 

 theory, and the results will be included in a detailed report of 

 the various bacteria occurring in the udder. 



ZOOLOGY. — On certain aspects of the bathymetrical distribution 

 of the recent crinoids. Austin H. Clark, National Museum. ^ 



In bridging the gap which lies between the conclusions deduced 

 from the facts gathered through the study of palaeontology — 

 which gives us a more or less detached series of instantaneous 

 flat views of local littoral conditions covering an immense period 

 of time — and the conclusions deduced from the facts accumulated 

 through the study of marine zoology — which permits a prolonged 

 examination of a single stereoscopic view — the two prime requi- 

 sites are: (1) to discover some means of adding geographical and 

 bathymetrical perspective to each of the palseontological pic- 

 tures, and (2) to discover some means of calculating geological 

 time based upon the internal characters of the recent animal 

 groups without reference to their fossil representatives. 



The comparison between recent marine types and their fossil 

 representatives, while yielding results of the greatest value, is 

 open to two objections: (1) it necessarily takes no account of the 

 ability of many types to persist in specially restricted localities 

 where they stand little or no chance of preservation, yet where 



1 Published with the permission of the Secretary of the Smithsonian Institu- 

 tion. 



