WILL SCOTT. 



upon : (i) the production of the plankton in the ponds, (2) the 

 overflow of the ponds into the subterranean passages, (3) the 

 dilution by rain water and interstratal seepage, (4) the rate of 

 current in the cave stream, (5) the ability of the planktonts to 

 live in the cave environment. 



Local Distribution. - - Observations taken at Dalton Cave and 

 at Shawnee Cave indicate that the amount of plankton in the 

 lower portion of the cave is less than in the upper portion, the 

 amount at Shawnee varying from 40 per cent, to 80 per cent, of 

 the amount at Upper Dalton. This is due, I think, principally 

 to the destructive influence of the cave environment (see Table 



III.). 



TABLE III. 



Genus Number per Number per 



or 200 gal. at 200 gal. at 



Class. Upper Dalton Cave. Shawnee Cave. 



Cyclops 59 41 



Nauplii of Cyclops 89 64 



Daphnia (immature) O I 



Difflugia II 3 



Arcella I O 



CEdogonium i o 



Pandorina 2 o 



Rotifera 2 4 



Total 165 113 



P ceding and Reproduction of the Plankton in the Cave. The 

 alimentary tracts of the Crustacea always contained some food. 

 In the alimentary tracts of Cyclops and Bosmina at ordinary 

 stages of the cave stream, there was nearly as much food as in 

 members of these genera taken above ground. In the lower 

 stages of the stream the amount of food contained decreased. 



Eggs were common in the egg sack of Cyclops, in the brood 

 chambers of Bosmina, and upon Anura cocJilearis, They were 

 also observed in Daphnia, but the individuals of this genus were 

 rare. 



Nauplii of Cyclops were common throughout the year and the 

 young of Daphnia and Bosmina were observed. 



It is evident that some of the planktonts are able to continue 

 their nutritive and reproductive processes under cave conditions, 

 although this environment inhibits them. Whether these forms 





