48 BOTANICAL GAZETTE [JANUARY 
which has always been separate, and one from which the first 
and second and the marsh north of the road have been derived. 
The original lakes were some 5 to 6* (1.5—-1.8™) higher than at 
present, as is shown by a beach or terrace north of the second 
lake, and by other evidence. Their lowering is apparently due 
in great part to better drainage since open ditches have been 
cut in the outlet channels. 
It is very desirable that a complete enumeration and com- 
parison of the fauna and flora of the first and second lakes 
should be made. Here are two lakes that once were one, but 
except for the connection through ‘a ditch running only in the 
spring, have been isolated for a long period. The physical 
characteristics of the two lakes are now very different, and, 
assuming that they were both inhabited by the same forms when 
there was one uniform condition, it would be reasonable never- 
theless to expect modifications or variations to arise, particu- 
larly in the aquatic life, following the changes in external con- 
ditions. Some differences in the present plant life of the two 
lakes are now very noticeable, the phytoplankton of the first being 
very different from that of the second. The latter contains an 
enormous number of blue-green algae, Oscillaria and others, or 
at least did all through the winter and spring, while the first 
lake had none. Desmids appeared in great abundance in a 
culture dish from the first lake, while the other gave few. More 
diatoms have been present in the second lake than in the first. 
The second contains many Volvox, not found at all in the first, 
and some Eudorina. Two representatives of the Peridineae, 
Peridinium tabulatum Ehrh. and Ceratium hirudinella O. F. Miller, 
occur in each lake. The paucity of higher plants is noticeable. 
The first lake has no Elodea or Myriophyllum, only three 
species of Potamogeton, little Ceratophyllum, and but two small 
clumps of Chara, The flora of the second lake, not yet suffi- 
ciently studied, is apparently quite as scanty. The presence or 
absence of flowering plants seems to be largely a matter of the 
chances of dispersal, but this certainly does not account 
for the differences in the phytoplankton of the two lakes. In 
seeking an explanation of this account must be made of their 
