276 



THE AMERICAN NATURALIST 



[Vol. XLI 



plant parasitism, plants parasitic on animals, animals parasitic on 

 plants, animal parasitism, the role of parasites in pathology, and 

 finally parasitism in the evolution of species. This last chapter 

 presents in striking fashion an opinion previously advanced by this 

 author regarding embryonic and sexual parasitism. 



In the second part, devoted to mutualism, are grouped under separate 

 chapters discussions of social life among plants, mutualism between 

 plants and animals, social life among animals, and mimicry. Under 

 these headings are discussed many interesting questions of an unusual 

 sort. The author has selected instances of an illustrative tyj)e and 

 presents them clearly and attractively. 



The scope of the work is uncommonly large, einhrac iuo- ;,s ii does 

 both plants and animals and scant 300 pages are narrow limits in 

 which to present such discussions in a form to escape criticism. To 

 a zoologist it appears as if on the whole too great space had been given 

 to the plant side and yet this may be distorted perspective on the part 

 of the reviewer. The figures deal almost exclusively with plants and 

 insects, with the former largely in the majority. 



In many respects the work hardly represents present knowledge 

 on the subjects discussed. Thus, in speaking of the hookworm, to 

 which the author devotes a considerable' section, the statements tiiat 

 this parasite sucks blood is jx'rliaps excusable, thouirli in WHY.', Loo^^ 



upon and quoted, as well a> <(Mifinncd, since then. However to 

 outline the life history with the larva cnevMed in a roisiant envelope 

 and infection takinn- place by the inoulli astoiu.hiiin' i„ view of th-- 



