There are several conflicts in the published records on 

 bird temperatures which are probably due to differences 

 brought about by season, sex, struggling, and, too, in the 

 early records, by imperfect instruments, for the modern ac- 

 curate self-registering clinical thermometer was unknown to 

 Milne-Edwards and his predecessors, its substitute being a 

 crude affair, and such as it was, only just beginning to be 

 used in physiological and clinical investigations. 



Sutherland (112) concluded from his study of bird tem- 

 peratures that "the result seems to show that the higher the 

 bird in the zoological scale, the higher in general is the 

 temperature of the blood"; in other words, sis birds have 

 risen in the zoological scale, their temperatures have become 

 elevated pari passu. In general, this conclusion is svibstan- 

 tiated by Table No. 6. If the writer is not in error, what 

 occurs in the whole class Aves is also found more or less 

 within the orders and families of the class — i. e., differences 

 of "highness," both in taxonomy and of temperatures, in 

 orders and in families ; if this be true, a steadily rising curve 

 of the temperatures found in the class Aves would not only 

 be unexpected but it would be suspicious. 



What one would anticipate under these conditions is a 

 more or less steadily rising curve, subject to undulations 

 which are brought about by differences of temperature in 

 the families of the orders involved ; this anticipation is real- 

 ized to a reasonable degree by the temperatures in Table No. 

 6, which show a distinct tendency to rise with the species, 

 and be subject to undulation when the linear classification 

 jumps from family to family. It seems to me that there is 

 more than chance in the parallelism between the rising body 

 temperature and the bird's elevation, despite the scanty 

 data, and despite the probable errors in both the data and 

 the classification. 



Let us see if any other writers have been convinced of 

 this relation; Pembrey (156) says, "those animals which 

 are higher in the scale of evolution, such as birds and mam- 

 mals, have a high temperature, which is fairly constant and 

 independent of the temperature of the surrounding air." 



Simpson (165) seemed surprised to find that different 

 families of the same order exhibited different temperatures, 

 saying, "even families of the same order appear to differ 

 considerably in body temperature," which, rather than a 

 surprising thing, is what ought to occur if Sutherland's law 

 be correct and apply to orders and families as it seems to 

 apply to the class. Simpson appears to have been familiar 

 with Sutherland's conclusion, and after denying that there 

 is a relation between the highness of a mammal and the ele- 

 vation of its temperature, he says that "the same appears 

 to be the case amongst Class Aves, above the Ratitse." I take 



58 



