246 NATURE STUDY REVIEW [7 :8— Nov., 1911 



domestic processes that she uses in a mechanical way without 

 perhaps knowing the reason therefor. Not the least suggestive 

 chapter is that on practical suggestions which applies the 

 knowledge gained to the avoidance of disease in the common 

 daily living. Withal the book is a welcome addition to the 

 texts serviceable in study of the lowly plant from the practical 

 point of view. 



W. E. Castle's recent volume entitled Heredity is an ex- 

 cellent illustration of how deeply one may be led into the 

 profound problems of science by a serious study of children's 

 pets. The book deals largely with guinea-pigs, rabbits and 

 white mice. It is a discussion of the experimental studies 

 which have created our exact knowledge of heredity. Castle 

 has himself contributed largely to this knowledge by his own 

 work in breeding. The results are not only illuminating to the 

 scientist from a theoretical point of view but of immense prac- 

 tical importance to the breeder, giving him a foundation of 

 fact by means of which existing strains may be improved and 

 new breeds created. The introduction states the problem of 

 the new science of genetics. The first chapter emphasizes the 

 duality of inheritance, the distinctness of paternal and maternal 

 elements. Chapter two states clearly some evidence for the 

 principle which Castle and many other biologists maintain that 

 the germ plasm, the hereditary substance, is quite independent 

 of the rest of the body. Chapter three discusses Mendel's law, 

 the basis of our knowledge of this subject. Succeeding chapters 

 give a resume of the modifications of this law since its redis- 

 covery in 1900. The book is well illustrated with pictures of 

 the animals that have served Castle so well in his investigations ; 

 some of these same animals are shown in cuts illustrating 

 Professor Castle's article in this number of the Review. The 

 book is concise, lucid and accurate, giving the lay reader a 

 vivid notion of the present state of our knowledge of heredity. 

 It is not a nature-study book in the sense that the material in 

 it will furnish subject matter for grade work. It will give the 

 nature-study teacher an outlook, however, into the regions 

 whither her subject leads and an inspiring contact with the keen 

 mind of a man who stands on the firing line of scientific advance. 

 Such broad visions are needed even to teach elementary science 

 most efficiently. [D. Appelton & Co., $1.50.] 



