112 Roosevelt Wild Life Bulletin 



This ditferentiatiun based upon depth should not Ije upon some 

 arbitrary depth but upon the basis of thermal stratification. If 

 ponds are defined as bodies of water without thermal stratification 

 we find that most of the waters of the Park region are of the pond 

 type; IMombasha, Popolopen and Island- Lakes being the only 

 true lakes. On the basis of quantitative distinctions between the 

 heleoplankton and the limnoplankton my observations agree with 

 those of Whipple ('14) and Huitfeld-Kaas ('09) who hold that 

 shallow bodies of water produce proportionally greater masses of 

 plankton, instead of those of \\'. & G. S. West ("04, '09) who 

 state that the plankton production is generally greater in large lakes. 

 As has been shown above, environment plays an important role, 

 but other things being equal shallow lakes have a greater bulk of 

 plankton. 



Attempts have also been made to classify the plankton flora on 

 the basis of the constituent organisms and without particular refer- 

 ence to morphometric considerations. The first of these attempts, 

 that of Apstein (96), divides the lakes into the Chroococcus and 

 Dinohryon types. The former are characterized bv numerous 

 Chroococcaceae (PL 3), comparatively few Dinohryon colonies 

 (PI. 5, Fig. 7), and a general quantitative richness of the phytoplank- 

 ton : the latter have few Chroococcaceae. numerous Dinohryon colo- 

 nies and clear waters, owing to the small bulk of the plankton. Alany 

 have obiected to this system of classification and have cited lakes 

 that fail to conform to Apstein's svstem of classification. Amberg 

 ('00). Huitfeld-Kaas ('06) and Plumiccke (14) have shown lakes 

 where this classification breaks down. G. S. West holds that 

 Apstein is fundamentally correct in making a distinction between 

 dift'erent types of plankton floras, but his division is not sufficiently 

 far-reaching, especiallv in view of the desmid tApe of plankton 

 formation. Lakes with a rich desmid flora were first discovered in 

 Scotland by \W & G. S. West (03). but they are now known to 

 exist in the Scandinavian peninsula (Huitfeld-Kaas, '06: Teiling. '16; 

 Strom, 21), Ireland {\\ . & G. S. West, '02, '03), Africa (G. S. 

 ^^'est, '07"), Australia ( G. S. West, '09) and North America. This 

 plankton flora, in which desmids form a conspicuous feature, has 

 been called the Caledonian plankton formation by Teiling ("16) 

 in contrast to the Baltic tvpe where there are few desmids. In 

 contrast with these views Wesenberg-Lund ('08) holds that the 

 plankton community contains the same types everywhere, and nearly 

 evervwhere the same species, and that attempts fail when they trv 

 to divide these organisms into phytogeographical communities, since 

 there are no sharplv delimited areas of distribution of certain species 

 or genera. The sharplv defined Caledonian formation that W. & 

 G. S. AVest have noted is clearlv discernible in certain lake areas oi 

 the United States : and Telling's two classes — the Caledonian witli 

 a conspicuous desmid content, and the Baltic with a rich blue-green 

 algae content — should be recognized. The distribution of Di)W- 

 bryon. and for that matter of other plankton Phaeophyceae (PI. 5) 



