502 



THE AMERICAN NATURALIST 



[Vol. LI 



same as the one distributed by Miss Tilden from the Great Salt 

 Lake and named by her Aphanothece utahensis. On the au- 

 thority of Professor Setchell, we shall designate it Aphanothece 

 packardii. 



The plant occurs in small masses, irregular in size, floating in 

 the water and piled up by the waves on shore. These masses 

 show a gradation in color from a deep blue-green, to light brown, 

 and some were colorless; this depending, no doubt, on the con- 

 ditions of the plants in the individual clumps, and not, as has 

 been suggested,* on a variety of species in the clumps. Micro- 

 scopic examination of this material shows the individual plants 

 in the mature condition, and also in various stages of division 

 by fission. Great numbers of the cells are held together by their 

 gelatinous secretions. The individual plants average about two 

 micra in diameter. 



Microscopic examination of the lake water reveals at least two 

 species of diatoms. They probably belong to the genera Navi- 

 cula and Cymbella. These plants do not occur in suflficient num- 

 bers, in the denser water about Saltair, to be seen with the naked 

 eye. 



The fact that putrefaction and decay are taking place in the 

 water, especially near to shore, where organic material is abun- 

 dant, shows conclusively that bacteria are present. 



Here it may be well to suggest that at least some of the plants 

 distributed by Miss Tilden as Great Salt Lake plants, in all prob- 

 ability came from the fresher waters at and near the mouths of 

 rivers, or in the bays formed by the rivers at their place of en- 

 trance into the lake. As tlie present observations were confined 

 to the denser waters, even an indication of the plants referred 

 to— with the one exception noted— was not found. 



For the physiological work, water was transferred from the 

 lake to the laboratory, in sufficient amount to make a number of 

 series of dilutions in glass aquaria. These series included solu- 

 tions of different density, varying in specific gravity from 1.0115 

 to 1.222, a saturated solution. 



Masses — large in some series, but small in one — of Aphano- 

 thece packardii were placed in these solutions, and, in every case, 

 enough Chlamydomonas was thus introduced to start a more or 

 less flourishing growth. 



From time to time, measurements were made of the Chlamy- 

 domonas present in the solutions, and during the first few 



* Talmage, J. E., "The Great Salt Lake— Present and Past," p. 76. Salt 

 Lake City. 



