EXPERIMENTS IN THE BREEDING OF CERIONS. 



BY PAUL BARTSCH. 



In 1912, by invitation from the Director of the Marine Biological 

 Laboratory of the Carnegie Institution of Washington, and through 

 the courtesy of the Secretary of the Smithsonian Institution, I had an 

 opportunity to visit the Bahamas and to make personal observations 

 upon the Cerions on New Providence and on Andros in the region of 

 South Bight. 



On this expedition we found that Cerions were very abundant 

 wherever they occur, that they live close to the seashore, but never- 

 theless remain well beyond the reach of the ocean spray. They never, 

 therefore, live outside of the hurricane rampart of the exposed shores. 

 They are usually on the lowland flats, but under favorable circum- 

 stances may climb the hills, for example Driggs Hill or Morgan's Bluff 

 at Andros and the sea bluff at Jeremie, Haiti. This partiality to the 

 coast lands is probably responsible for their discontinuous distribution, 

 practically resulting in the formation of isolated colonies, and a great 

 number of closely related forms scattered over the entire Archipelago 

 of the Bahamas. 



By taking material gathered from such a colony and noting all 

 measurable characters present ad by its members, one obtains a mode 

 different from that which may be secured in a similar manner from 

 an adjacent colony. Each colony, therefore, presents certain slight 

 characters by which we can distinguish its members from those of other 

 colonies. 



The question arises, are the forms in the various colonies fixed forms; 

 that is, will generation after generation yield the same mode in measure- 

 ments, or will changes in the local environment from season to season 

 affect the developing organisms to such an extent as to produce an 

 unending series of slight variations? These were the problems that 

 called for a solution. The hope of throwing some light upon these 

 questions prompted the breeding experiments which were started in 

 1912 and have been followed up ever since, and upon which the follow- 

 ing reports have been published from time to time : 



Planting Bahama Cerions upon the Florida Keys, Year Book No. 11 of the Carnegie Insti- 

 tution of Washington, 1912, pp. 129-131. 

 Report of Results of the Planting of Bahama Cerions on the Florida Keys, Year Book No. 



12 of the Carnegie Institution of Washington, 1913, pp. 169-172. 

 Preliminary Report on the Bahama Cerions planted on the Florida Keys, Year Book No. 



13 of the Carnegie Institution of Washington, 1915, p. 196. 



Experiments with Cerions in the Florida Keys, Smithsonian Miscellaneous Collections No. 

 6, 1915, illustrations 38-40. 



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