REVIEWS 5i7 



This is undoubtedly a very interesting book, and one which we consider of 

 value to the student of Man and Modern Civilisation. It is daringly written, and 

 is bound to stimulate interest in the various problems the author has discussed. 



J. Bronte Gatenby. 



Heredity. By Prof. J. Arthur Thomson, M.A., LL.D., Professor of Natural 

 History in the University of Aberdeen. Third Edition. [Pp. ix + 627, 

 with 47 illustrations.] (London : John Murray, 1919. Price 15^. net.) 



This is the third edition of Prof. Thomson's book. The author is such a great 

 authority on all aspects of heredity that one hardly needs to comment on this 

 new edition. For one who wishes to have a reliable work on Heredity and Sex, 

 and especially on the philosophy of these subjects, Prof. Thomson's book is 

 recommended. In the present edition a great deal of the newer evidence on 

 Heredity has been introduced, and the Professor has managed to deal with 

 several very bitterly debatable questions with fairness. We consider the cytology 

 rather weak, but we know of no other book of such wonderful value to the lecturer 

 and student. It is a colossal mine of learning in all matters relating to Heredity, 

 Sex, and Mendelism. 



J. Bronte Gatenby. 



The Elementary "Nervous System. Monographs on Experimental Biology, 

 By Prof. G. H. Parker, Sc.D. [Pp. 229, with 53 illustrations.] (Phila- 

 delphia and London: J. B. Lippincott Company, 1919. Price 82.50 net.) 

 [Second Review.] 



Prof. Parker's papers have already established his reputation as an authority 

 on the nervous system of the lower animals, particularly on that of the Coelen- 

 terates and Porifera. The present work, being the second of the Monographs on 

 Experimental Biology issued under the editorship of Jacques Loeb, T. H. Morgan, 

 and W. J. V. Osterhout, makes accessible, in a very readable form, the general 

 conclusions he has reached, and reviews the evidence by which he has reached 

 them. 



The subject is one that has received a certain amount of attention previously, 

 but scarcely as much as its interest and importance warranted, from workers who 

 have approached it from either the anatomical or the physiological point of view, 

 but rarely both. Prof. Parker has used both methods side by side with striking 

 success, and so gives another example of the importance of not separating the two 

 methods of approach which should, of course, go hand in hand in all biological 

 inquiry. 



Starting with the lowest of the Metazoa (the Sponges), the motor mechanism is 

 described, and we find in them, as in lowly Coelenterates, that the unit is a 

 " primitive type of muscle tissue . . . unaccompanied with nervous elements " 

 This simple tissue is capable of receiving and responding to external stimuli. In 

 some of the Coelenterates this simple mechanism has advanced to the extent of 

 the epithelio-muscular cell being differentiated into two portions. One part of the 

 cell, situated externally, is receptive in function, and the other internal part is 

 contractile. Next, in the higher Coelenterates, we find a receptor element (the 

 sensory cell) and a separate effector element (the muscular cell). Still, in the 



