1918] ELMORE—DIATOMS 189 
cate that diatoms are not very sensitive to such changes. Also, 
the fact ‘that Lake I, which contains about the same amount of 
solids as Court Lake, but has recently been connected with the 
main lake, has a diatom flora much more like the main lake than 
like Court Lake, also indicates that diatoms are slow in responding 
to changes in environment. 
No marine species were found in any of the outlying lakes, but 
as they are comparatively rare in the main lake, and the other lakes 
have been less carefully explored, this fact probably has no signifi- 
cance. More careful collecting may show them there also. 
In a spring at Sully’s Hill on the shore of the lake, but at an 
elevation of 50 ft. or more above it, 9 species were found, 3 of which 
were found in the lake and 6 not found in it. These probably 
have no relation to the diatoms of the lake, for there has never been 
any connection between the water of the two places, and these 
diatoms are all of species found commonly in fresh water everywhere. 
In ditches along railroads and in pools 26 species were found, 
17 of which were found in the main lake and 9 of which were not. 
The composition of the water in these places varies greatly. After 
rains, when they are filled, the water is practically fresh, but as it 
evaporates it becomes considerably concentrated. This, together 
with the fact that this land was once covered by the lake, explains 
the presence of the forms commonly found in brackish water. 
Some of these facts are summarized in following table I. 
TABLE I 
HABITAT AS REPORTED ELSEWHERE 
Spe- Inot in| Percent-| ,, Time 
Place cies in | Main | age of | Separated Fresh Marine| Fresh, 
man | lak lida | fom main . | and |Brack-| or |brack- 
lake a ane lake | Fresh |Marine| pyack-| ish |brack-| ish, or 
ish ish | 
ain Lake. .... 56 O28 isi ae 25 4 | 20 3 2 2 
Minnewaukon 
ag dee es 13 I | ©.4464/6 months} 6 I 6 ° ° I 
Court Lake... .. 9 | 13 | 0.12 |100years} 16 ° 4 I f ° 
ORE Sic: I 6 | 0.1328) 5 years) 12 °o | Io I I e 
Pools and ditches} 17 | 9 |.....:.J}.....00- 14 ° I 3 ed 
The diatoms of this region illustrate what has commonly been 
observed elsewhere, that many of them adapt themselves readily 
