76 ROBERT M. YERKES 



Both methods, when carried to extremes, lead to false or inane, or, at best, very 

 partial interpretations — the scientific to a kind of animal phoronomy, hke the 

 reflex-theories of Bethe and Uexkiill, the intuitional to the humanizing of animals 



and all the perversities of the American "nature fakers." If I decline 



to join the ranks of those whose only ambition is to describe and measure the visible 

 movements of animals, and am willing to resort to a comparative psychology in 

 which inferences from analogy with our own mental processes shall have a place, 

 I do this, not because I believe that the former course would be altogether unfruitful 

 or uninteresting, but because the latter seems to me to promise a deeper and more 

 satisfactory insight into the animal mind." (pp. 505, 506, 507.) 



Polymorphism receives thorough and illuminating discussion, as do also 

 such topics as the history of myrmecology, the classification and distribution 

 of ants, and fossil ants. A fascinating chapter, XI, on the habits of ants in general 

 prepares the way for detailed accounts of the habits and instincts of the pomerine 

 ants, the driver and legionary ants, the harvesting ants, the fungus-growing ants, 

 and the honey ants. I quote a fragment from chapter XI to indicate the nature 

 of the treatment of habit. 



" Having previously described the nuptial flight the author continues his account 

 of the behavior of the female thus. " On descending to the earth the fertilized 

 female divests herself of her easily detached wings, either by pulling them off with 

 her legs and jaws or by rubbing them off against the grass-blades, pebbles or soil. 

 This act of dealation is the signal for important physiological and psychological 

 changes. She is now an isolated being, henceforth restricted to a purely terres- 

 trial existence, and has gone back to the ancestral level of the solitary female 

 Hymenopteron. During her life in the parental nest she stored her body with 

 food in the form of masses of fat and bulky wing-muscles With this physiological 

 endo"muent and with an elaborate inherited disposition, ordinarily called instinct, 

 she sets out alone to create a colony out of her substance. She begins by excavating 

 a small burrow, either in the open soil, under some stone, or in rotten wood. She 

 enlarges the blind end of the burrow to form a small chamber and then completely 

 closes the opening to the outside world. The labor of excavating often wears 

 away all her mandibvilar teeth, rubs the hairs from her body and mars her burnished 

 or sculptured armor, thus producing a number of mutilations, which, though 

 occurring generation after generation in species that nest in hard, stony soil, are, 



of course, never inherited "(PP- 184, 185.) The chapter consists of just 



such clearly drawn and interesting pictures of ant life as this. 



Of the special habits, and other activities and relations, which receive con- 

 sideration, mention may be made of nest-building, compound nests, the relations 

 of ants to plants, to other insects, and to one another. The chapters on parasitism 

 and slave-making are especially valuable, for they make available in readable form 

 a mass of information which is of extreme importance for a true appreciation of 

 the social life of ants. 



Last, and for the student of the mind of animals most important, the chapters 

 on instinct and intelligence may be characterized. They are full of facts, rich 

 in penetrating analyses, stimulating and encouraging to those who despair of the 

 solution of the problems which center about these concepts. Again the author 

 may be permitted to speak for himself. 



" If ants exhibited merely the reflexes, or such brief and simple responses to 

 sensory stimuli as we have been considering in the preceding chapter, their lives 

 would flow on with the same monotonous regularity as those of many other insects 



