778 



THE AMERICAN NATURALIST [Vol. XL 



States At^rieiiltiiial Department. The indirect results of hunger 

 may be, therefore, (piite as effective as actual starvation. 



Animals vary greatly in adaptability to new conditions caused 

 by prolonged cold and heavy snowfall. Horses remove snow even 

 to depths of three or four feet and find food to carry them through 

 the winter, while cattle under the same conditions starve. 



An interesting instance of the effects of a temporary lowering 

 of temperature in a subtropical region is that cited by Bangs of 

 the influence of an unusual cold wave in the habitat of one of the 

 Sirenia {Manatm manatus) in the rivers of Florida in the winter 

 of 1895. The author observed that an unusual cold wave cut 

 down all the leaves of the mangrove, a favorite food of the manatee 

 at certain seasons. This was followed by a marked numerical 

 diminution of the manatee.^ 



Dauc,n-s of Xuwrrical Dimhiufmn and DlwuilM Herds.— 

 While distinction must l,e <lrawn brtuvcn actual <>xtincti(m and a 

 tcmpomrij (limiiiiition in numbers (aused, for example, by cold 

 waves, prolonged or repeated droughts, floods, epidemics, and 

 other unfavorable conditions of life, it is very important to observe, 



extinction in certain cases. For example, a herd of animals may 

 l)e re.hiced to the danger point in tnnnl)ers where they can no 

 longer protect their young. Director Bell of the Canadian Geo- 

 logical Surv<'y believes that the small herd of Woodland Bison of 

 Hriti>h Columbia, now thoroughly protected by the government, 

 will be destroyed gradually through the killing of the calves by 

 wolves, the bulls not being sufficiently numerous to protect the 



On this fa"'nuliar subject .>ee (''errit S. >'liluVs-'\lrilr L^i^^^ 

 the Furopean Hi.on Herd," in which the author dmw> the pos- 

 sil>ly fatal influenc<- of inbree.ling on din.iuished hvuU, although 



