PAPERS PRESENTED AT GENERAL SESSIONS 93 



temperature, and an increase in the soluble materials in 

 the newly built tanks, a combination which was serious 

 for so delicate a fish as the rainbow trout. On July 17, 

 it was deemed that the increase of Devils Lake water had 

 been carried to a point where undiluted lake water might 

 be used. Xo serious results were noted. 



These fish were fed macerated liver. Most of them fed 

 freely and were active, thri\dng, and growing. Some of 

 them refused to eat from the beginning of the experi- 

 mental period, and did not grow, but remained in an ab- 

 normal condition throughout the entire time they were 

 kept in captivity. On August 14, 48 were transferred to 

 the floating fish pen in the lake. Several of these trout 

 were diminutive and represented the starved, unuour- 

 ished members which had sui*vived. Two weeks later, on 

 August 29, .34 rainbow trout, after 98 days of experi- 

 mental work, were turned into the lake. They had gi-own 

 from 21 2 centimeters to Sio centimeters. They were ex- 

 ceedingly active and vigorous and seemed to be wholly 

 adjusted to their new surroundings. "While the experi- 

 ments with the rainbow trout were attended with far 

 greater losses than was the case in the experiments with 

 the perch, the final results indicated that we were ap- 

 proximating very closely proper methods of accli- 

 matization when we were able to save any of the exceed- 

 ingly delicate rainbow trout and secure marked growth 

 and great vigor and activity in the stock which Avere 

 turned loose at the end of the 98 day experiment. 



As previously stated, to the plant and animal physiolo- 

 gist it is obvious that biological studies in the waters of 

 a dying lake afford! conditions not only for interesting ad- 

 justments within the cells of the organisms ex]Derimented 

 with, but there is afforded also a remarkable opportunity 

 of investigation for all kinds of cellular biology. This is 

 particularly true in the study of phyto-plankton. The 

 changes in the membrane, the plasmolysis, and the gradu- 

 al acclimatization in acquiring the ' ' euryhyaline habit", 

 as Professor Oltmanns expresses it, may be studied with 

 the one cell organism in a remarkably successful manner. 

 While one does not attempt to draw general conclusions 

 from a few isolated experiments, nevertheless he is con- 



