LITERARY NOTICES 



Physiology of Central I^ervous Organs.^ 



The necessity of a physiological consideration of problems in zool- 

 ogy has been forcing itself in the last five years upon the attention of 

 students. Heretofore physiology has been in the main a study in the 

 medical school centering about the human being or at the best dealing 

 with other members of the vertebrate series as a means of elucidating 

 problems in human physiology. As opposed to this a few original in- 

 vestigators have recently gone to the opposite extreme and have initiated 

 the study of protozoan physiology without apparently appreciating the 

 fact that protozoan physiology may be as special as human physiology. 

 Notwithstanding the Umited nature of this new movement, important 

 results have already been achieved by it and, if one bears in mind that, 

 like human physiology, it is bringing to light material for a compara- 

 tive physiology and that it is not and cannot be comparative physiology, 

 no great harm has been done by the enthusiasm of its supporters. 

 Comparative physiology in the modern sense is essentially an unex- 

 plored region, and it is, therefore, a matter for congratulation when one 

 who has spent much of his time in opening up this new domain, turns 

 aside long enough to describe the general features of those parts with 

 which he is most familiar. This has been done for the nervous system 

 by Professor Loeb in his book entitled, Einleitung in die vergleichende 

 Gehirnphysiologie und vergleichende Psychologic. 



In the introductory chapter certain fundamental conceptions are 

 considered. The physiological unit of nervous activity is the reflex. 

 This is usually supposed to be purposeful and by some investigators 

 maintained to involve, if not in its execution, at least in its development, 

 some trace of intelligence and therefore to be a product of ganglion 

 cells. But, as plants respond to light with as much reflex accuracy as 

 animals, it is obvious that reflex action not only is not necessarily asso- 

 ciated with ganglion cells but not even with a nervous mechanism ; it 

 may be a property of relatively undifferentiated protoplasm. The differ- 



* Einleitung in die vergleichende Gehirnphysiologie und vergleichende 

 Psychologie. Mit besonderer BeriJcksichtigung der wirbellosen Thiere. Von 

 Jacques Loeb, 207 pp., Verlag von J. A. Earth, Leipzig, 1899. 



