G- GENERAL NATURAL HISTORY AND ZOOLOGY. 323 



ward of localities hitherto assigned them. Northern species 

 were also met with at points considerably farther south than 

 their previously known range, having been found breeding 

 above the timber line in Middle Colorado. The imaginary 

 boundary of the eastern and western species, as existing along 

 the 100th meridian, heretofore suggested, Mr. Allen is there- 

 fore inclined to remove, and to look to the extension of for- 

 ests and plains, as well as of wooded river-bottoms, as deter- 

 mining the limits of the range of the birds. In consequence 

 of the great irregularity of the surface, the fauna? of the mid- 

 dle and western portion of the continent have very irregular 

 and broken areas, the more southern, while occupying the 

 lower table-lands, extending also up into the lower mountain 

 valleys to a limit varying with the latitude and the peculiar 

 local condition of the valleys themselves. Above this basal 

 zone are several other zones, which are continuous for con- 

 siderable distances along the main chains, but also embrace 

 distinct insular patches in the more isolated groups of mount- 

 ains. The higher zones are still less regular in their continu- 

 ity and in their respective areas, the highest having an arc- 

 tic character, and occupying only the partially snow-covered 

 summits that rise above the limit of tree growth. BuU.Mus. 

 Comp. Zoology, III., vi. 



NEW THEORY OF ANIMAL HEAT. 



In a paper by Blondeau upon Pulmonary Respiration and 

 Animal Heat, exception is taken to the idea that animal heat 

 is due to the direct combustion of carbon and the hydrogen 

 of the blood by the oxygen of the air in the lungs and blood- 

 vessels, and an attempt is made to prove, by reasoning and by 

 experiment, that the carbonic acid which is disengaged in the 

 act of respiration proceeds, in part, from a fermentation which 

 takes place in the interior vessels, and from the combustion 

 of products which results from this fermentation, the blood 

 globules themselves, in his opinion, being only the globules of 

 a ferment presenting the closest analogy to the yeast of beer. 



He also maintains that the sugar contained in the animal 

 system under the influence of the blood-globule ferment is 

 transformed into alcohol and carbonic acid, and that the for- 

 mer of these bodies is burned by the oxygen of the air. 4 B, 

 August, 1872,631. 



