514 SCIENCE PROGRESS 



ZOOLOGY 



Upon the Inheritance of Acquired Characters : A Hypothesis of Heredity, 

 Development, and Assimilation. By Eugenio Rignano. Authorised 

 English Translation by Basil C. H. Harvey, Assistant Professor ot 

 Anatomy, University of Chicago. With an Appendix upon the Mnemonic 

 Origin and Nature of the Affective or Natural Tendencies. [Pp. 413.] 

 (Chicago: The Open Court Publishing Company, 1911. Price $2 net.) 



THIS work on a fascinating subject, by the distinguished editor of Scientia, should 

 have attracted more attention than it has in this country since its appearance in 

 English eight years ago. 



The author's main object is to elaborate a theory of development which he 

 terms "centro-epigenesis," the essential, conception in which is that there is a 

 central zone of development which exerts an infinite number of different influences 

 on the rest of the organism "by activating successively a regular series of specific 

 energies, each remaining in a potential state up to the time of its activation." 

 A subsidiary hypothesis to this main one is that each " specific nervous current " 

 from the central zone deposits a definite substance, and that this process is 

 reversible ; that is, this substance after deposition can provoke exclusively " the 

 same specificity of current " as that which deposited it. The author brings to 

 the support of these hypotheses a quantity of experimental work on development 

 and regeneration, drawing very largely on the work of Roux. 



With these hypotheses as a basis the author explains on the one hand the 

 inheritance of acquired characters, and on the other mnemonic phenomena, " in 

 the widest sense of the word." The book consisting thus of the presentation of 

 hypotheses, the acceptance or rejection of these must depend on the judgment 

 of the reader as to whether known facts support or contradict them, for the 

 questions with which they deal are far too subtle for the hypotheses to be put to 

 direct experimental proof. Probably the difficulties in the way of acceptance of 

 the hypotheses will appear greater to students of plants than to zoologists. Thus, 

 the author is forced to make assumptions in the case of plants such as that " one 

 must regard the leaf as the true individual, and one must attribute to it a 

 centro-epigenesis of its own " — a view which the student of the living plant will 

 most certainly reject. On the whole one feels that the author has been led to put 

 forward his hypotheses from a consideration of animals, and his ideas have been 

 applied to plants as well in order to speak of the organism in general. 



But whether the hypotheses are accepted or rejected, the book will be read 

 with great interest, both on account of the ingenuity of the writer in dealing with 

 the facts he cites in support of his hypotheses, and for his shrewd criticism of 

 pre-existing theories of development and heredity. He is, perhaps, at his best in 

 his trenchant criticism of Weismann, and in his discussion of the alleged cases of 

 inheritance of acquired characters, on which question he writes with great fairness. 

 The remarks on what constitutes an acquired character are especially noteworthy. 



It must be admitted that the language is sometimes vague. Thus, "phe- 

 nomena of nervous nature, in the widest sense of the word," might include almost 

 anything. Also, the author shows too much respect for the clever aphorisms of 

 which some writers of the past generation were unduly fond. Thus, Huxley's 

 definition of a plant as " an animal shut up in a wooden box " is a thing to be 

 forgotten— not to be quoted with approval. And to describe Haeckel's dogma that 

 ontogeny is a recapitulation of phylogeny as "the fundamental biogenetic law" is, 

 to put it mildly, an exaggeration. In the plant kingdom it is rather the exception 



