178 



BULLETIN OF THE BUREAU OF FISHERIES 



RESULTS 



"Bsnnal" individuals. 



6 individuals-6 trials 



2 individuals-2 trials 



The details of the results obtained in the work on yearling fishes and on toad 

 tadpoles are shown diagrammatically in Figures 1 to 7. These diagrams present 

 the results of 180 trials on a total of 247 fishes and 62 trials on a total of 181 tadpoles. 

 These trials comprise 46 series on fishes and 24 series on tadpoles. In addition to 

 the experiments represented in the diagrams, a relatively small number of trials was 



performed on mature sunfishes and 

 perch and on perch, bluegills, and 

 sunfishes less than 1 year old. 



The figures given above include 

 only experiments successfully com- 

 pleted under the conditions that 

 have been described and at tem- 

 peratures that seem to be signifi- 

 cant in indicating the limits of tol- 

 erance of the animals. They are 

 exclusive of a considerable number 

 of trials conducted at temperatures 

 that were found to be distinctly 

 above or below the limits of tol- 

 erance of the species. Such trials 

 were of some interest, however, 

 in indicating the consistency with 

 which, under the experimental con- 

 ditions, a graded series of temper- 

 atures affected the animals. 



Acclimatization 30°, 1 day 



32° 



5 indivldual8-5 trials 



trials 



Acclimatization 10°, 1 day 



30° 



4 indlviduals-4 trials 



Individuals -6 trials 



Acclimatization 10°, 4 days LIMITS OF TOLERANCE IN NOR- 



30 ° 32° MAL INDIVIDUALS 



The results obtained with nor- 

 mal individuals of the five species 

 of animals, which are summarized 

 in Table 2 and in Figure 8, may be 

 stated briefly as follows : 



1. The perch, which is typically a dweller in fairly deep water, has decidedly 

 the lowest resistance to high temperatures of any of the animals studied. 



2. The large-mouthed black bass, bluegill, and sunfish, which are, in the main, 

 shallow-water fishes, have resistances that are notably higher than that of the perch. 



3. Toad tadpoles, which normally live in shallow pools that are subject to wide 

 fluctuations in temperature, have a higher resistance than any of the fishes. 



10 individuals -10 trialG 6 indlviduals-6 trials 



Fig. 5. — Effects of high temperatures on yellow perch. For explanation 

 of symbols see Figure 1 



