BOOK REVIEWS 307 



realization of what it means Why not? What reasonable ex- 

 cuse can we have for doubting his understanding of what he is 

 doing?" (p. iS). I would reply to his "Why not?"-— the law of 

 parsimony, used everywhere in natural science, that (applying 

 it here specifically ) phenomena explained by instinct are never 

 to be referred to intelligence. These actions of the beaver, 

 complicated as they are, seem no more so nor more consciously 

 purposeful than the selection of the proper food plants for its 

 larvae by the milk-weed butterfly as it lays its eggs, or than the 

 excavation of a nest hole by a woodpecker. Yet these are re- 

 garded customarily as instinctive acts. 



He asserts that the beavers "are always ready to grapple with 

 new problems" (p. 46), which would be good evidence if true. 

 But the phenomenon he says is new, a heavy rain and consequent 

 rise of the river, is undoubtedly older than the beaver. Certainly 

 his discussion oi the beaver's intelligence shows little appreciation 

 Oi. the problems involved or familiarity with the literature ot animal 

 intelligence. His explanation of the development of instinct 

 is even more unscientific. A mother beaver assisted by the young 

 is working on the house (p. 8). "This needed more sticks and the 

 weak places had to be filled in with sod and mud. The young 

 assisted in this work, each bringing his small load and arranging 

 it as he had seen his parents do." (The italics are mine.) It is 

 unfortunate to have one's credulity shaken in the accuracy of 

 the observation by such inaccurate interpretation. The actual 

 statement of facts seems authentic, but it would have made a 

 stronger appeal if the author had been more cautious in his con- 

 clusions. 



The Butterfly Guide; A Pocket Manual. W. T. Holland. 



237 p. Doubleday, Page & Co. $1.00. 



This is another one of those handy guides similar to the bird 

 books, — guide, etc., from the same press. Some sixty pages are 

 devoted to the structure, life history and methods of collecting. 

 The rest of the book is made up of brief descriptions of the common 

 species, accompanied by the same illustrations (295) in color as 

 are found in the author's larger butterfly book. The author's 

 previous books are guarantee of the excellence of this one. 



