Fish Culture in Inland Waters 289 



Duseiibury stream where brook trout occur, with the following 

 results : 



" Fluctuations in water temperature in Dusenbury Brook between 

 2 p.m., August 6, and 3 p.m., August 7, 191 8: 



Date Time Air Temp. Water Temp. 



August 6 2 :oo p.m. 94 80 



August 7 7 :oo a.m. 79 67 



August 7 10:00 a.m. 80 68 



August 7 , 12 :30 p.m. 85 70.5 



August 7 1 130 p.m. 91 76.5 



August 7 3 :oo p.m. 94 80 



" The extremes of water temperatures as read are 67° and 80°, 

 a daily range of 13°. It is doubtful that the water temperature went 

 lower because the minimum air temperature recorded by the local 

 weather bureau was only 79°. From these readings it is evident 

 that the high-water temperatures are not of long duration [italics 

 the present writer's] , probably not longer than five hours. It is, 

 therefore, clear that some speckled trout experience no ill effect from 

 temperatures of 79° and 80° when only of short duration. While 

 it may be true that a temperature above 70° F. would be unsafe in 

 a crowded hatchery pond, the writer feels that for wild, rapid, 

 unpolluted streams the unsafe temperature is higher ; how much 

 so he is not prepared to say. The temperatures of 79° and 81° 

 as stated above, however, are very significant even though they may 

 not obtain in many trout streams. Notwithstanding these extreme 

 cases the writer prefers to err on the safe side and therefore recom- 

 mends as a basis for future stocking with brook trout that 75° F. 

 be taken as the dividing point between ' cold ' and * warm ' waters." 



Embody also refers to " other factors " than temperature to be 

 considered, saying that trout may thrive in one brook where the 

 temperature is 80° but not in another. This point has been dis- 

 cussed in preceding pages, but perhaps it may be well to suggest 

 that the same may possibly obtain with trout and 75° F. 



The present writer is inclined to regard it unwise to accept the 

 old views and conclusions as irrefutable unless they have been estab- 

 lished as scientific facts. He also recognizes that the term, " estab- 

 lished scientific fact," like " warm " and " cold " may be a relative 

 one. But any claim that the results of a very limited amount of 

 observation in a restricted field upsets all conclusions based upon 

 years of experience and observation in a wide field, should be care- 

 fully considered with all the evidence in hand. 



Embody's investigations are valuable and his observations in those 

 directions are commendable and should be continued. But, because 

 his observations appear to be at variance with the older ideas con- 

 cerning temperature, especially when he admits that other factors 

 are doubtless concerned, to attempt to explain the phenomena by 

 attributing them to " adaptation through natural selection," to the 

 present writer would appear to be dangerously near " deep water." 

 At any rate a discussion of that subject in this connection would 

 be out of place. However, it may be that the present writer is so 



