145 



in Ea.ule Lake. This iiiaterinl is so abundant that it gives the lake water a 

 decided amber color, and the rays of the snn penetrating- into the water 

 make sti*eaks much like those formed by sunlight entering into a vei7 

 dusty room, or dusty atmosphere, as in the phenomenon commonly spoken 

 of as the "sun drawing water." It is very certain that this material cuts 

 off a great deal of light, and perhaps absorbs considerable of plant food. 

 At any rate, there seems to be an interference of some sort between the 

 larger plants and the plankton— a fact generally obsei-ved. (See a reference 

 to this relation, part 5, page 257, of Science. Vol. XI, No. 268.) 



THE LAKE ALGAE.— No particular attention was paid to the Algae 

 except where they formed conspicuous masses. ^lost of the work in this 

 group was left to the investigators in plankton. Oedogonium, Cladophera 

 and Spirogyra could be found almost any time in the ditches and along the 

 edges of the lake. 



Throughout lioth summers of the work, 1899 and 190(1, Mongentia was 

 veiy abundant in the lalie, especially in the head bay. Much of it formed 

 immense cloudy patches among the water weeds, and much of it was in the 

 shape of lai'ge, floating, yellowish green patches. There was a good deal 

 of Rivvlaria in the lalve. All I saw here was attached. It grew in a semi- 

 globular form, fastened to water weeds and rushes. T'pon rich, muddy 

 bottom, where there is an abundance of dead bits of Scirpus, there is a good 

 deal of CJmctophora. \\h\ch assumes the form of a nan'ow, elongated, dichot- 

 omously branching thallus. which resembles some of the narrow liiccUt^ in 

 outward aspect. The water is full of tine granular masses of Clathrocystis, 

 and short, stout, rigid filaments of Oscillaria. which resemlile hair clip- 

 pings. Eydrodictyon is very peculiar in its occurrence in the lake. It sud- 

 denly appears in great masses at the mouth of Cherry Creek, and tlien. 

 after remaining a few days, it is washed in great masses upon the shore 

 and suddenly disappears, generally after reproduction, so that after the 

 large plants have disappeared the water is full of very tiny ones. The 

 date of appearance of this plant in 1900 was July 1.3. By .Tuly 27 all the 

 older Eydrodictynn had disappeared as a mass and the water was full of 

 young plants. 



Many large .Vo.s^oc-like jelly masses of an unicellular alga, probably 

 AphuHotheca, were found along the northern shore of the West baj'. 

 Among other algae noted in considerable masses was Microtliainmon. 

 There was also a few plants of a small momiliform species of Nitella found 



