54 SMITHSONIAN INSTITUTION 



My gathering of some 8.000 specimens in a space the size of an 

 ordinary room finally caused me to cast caution aside and to take a 

 large series of two races of these creatures with me to the Florida 

 Keys, and there to subject them to all possible conditions of environ- 

 ment and to watch for results. We marked the Bahama specimens 

 by putting tw^o fine, closely spaced file scratches on the shell of each 

 individual, and planted them in colonies of 500 each on Florida Keys, 

 beginning with the Ragged Keys a little south of Miami and con- 

 tinuing from there south into the Gulf to the Dry Tortugas. It was 

 somewhat of a surprise when we visited these colonies the next year 

 to find that no adult offsprings were present. The same surprise 

 was met the following year, and it was not until the third year that 

 we found Florida grown individuals that had attained a mature stage. 

 So one chapter was added to the life history of Cerions, that it took 

 three years for Bahama Cerions to mature, not a single season as 

 had previously been assumed. To this I may add that we have also 

 found that Cerions from Curcicao and the Greater Antilles require 

 an additional year to attain their full growth. 



Succeeding generations have been kept in isolated colonies, and 

 in that way we have been able to determine the part played by 

 changes of environment. Of course we expected that we would get 

 a broad expression of changes, for we had placed our colonies under 

 all possible conditions of habitat which we believed would affect their 

 food supply as well. At that time we believed that Cerions fed upon 

 the plants upon which they climb, another error that our observa- 

 tions have rectified, for we now know that they dine largely, if not 

 wholly, upon the fungal mycelia, minute plants and probably animals 

 living immediately below the surface of the ground. 



In our first experiments two species of Cerions were colonized on 

 the Florida Keys, namely, Ccrion casahlancac and Ccrion viarcgis, 

 the first coming from the south side of South Bight, and the second 

 from the north side of South Bight at its eastern end. The first series 

 of Florida grown offsprings secured showed no measurable charac- 

 ters diiTering from those found among specimens from the parent 

 stock from the Bahamas. The second generation proved equally 

 unresponsive, and it is tliis generation which is usually considered 

 the critical one by naturalists, and here we had looked for possible 

 expressions of changes due to the changed environment, for in this 

 generation both the germplasm and somaplasm had a chance to adjust 

 to the new environmental conditions. 



These experiments therefore proved that Cerions were not as un- 

 stable in characters as some had held, but rather the contrary. Since 

 then, other species have been added, namely, Cerion tiva from 



