Development of the Vegetation of New York State 93 
plex seed plants are also abundant and mask the algal mater- 
ial by their coarser structures.” 
Mud lake north of Bangor is cited as a specific case. 
This lake was visited at a time when ‘“ its waters were teem- 
ing with some species of minwte green floating plant organ- 
isms too small to be easily distinguished by the naked eye 
but readily made out with a hand lens and giving the water 
if seen in the proper ight a distinct greenish tint” ‘“ In the 
bottom of this lake and below the turf about its borders was 
a considerable depth of yellowish, fine grained, structureless 
peat, which on examination proved to be made up of the 
remains of similar minute alge.” ‘In northern Michigan 
there are several lakes that are nearly filled by the remains 
of such minute plants. In these lakes are forming beds of 
soft, light-colored peat, which differs so much from ordinary 
peat as to be easily distinguished by its fineness of grain 
and peculiar soft, cheesy consistency.” 
Instructive data in this connection are found in the work 
of Birge and Juday* upon the plankton of the Finger 
Lakes of New York. Thus the average number of diatoms 
per cubic meter of water in the first fifty feet in depth of 
Cayuga Lake was on August 12, 1910, about six million. 
In Conesus Lake, on August 25, 1910, the blue-green algz 
averaged about one-half million per cubic meter in the first 
thirty feet of water depth. 
(2) Normally Not Free-Floating Algal Vegetation. 
This purely arbitrary classification of vegetation elements 
aims to single out a relatively bulky amount of algal growth 
of fresh water lakes and ponds which, while not anchored 
to the lake bottom by root-like organs, normally les upon 
the lake bottom or is attached or adheres to submerged ob- 
jects — stems, and leaves of vascular water plants, trunks 
and branches of trees which have fallen in the water, ete. 
It may subsequently be broken loose by wave action or be 
buoyed to the surface by gas caught in the filamentous mass. 
1Birge, E. A., and Juday, C. A Limnological Study of The Fing- 
er Lakes of New York. Bull. U. S. Bur. Fisheries, vol. 32:1912. Doe. 
791, 1914. 
