250 REVIEWS HUMAN PHYSIOLOGY. 



mathematical, but certainly not biological; where all are dynamic, 

 the result at least of some principle or agency (the vital principle he 

 almost condemns, and yet offers no other "final cause" in its stead) 

 — no function, per se, can be regarded as statical when every thing is 

 marked by perpetual change, where in nutrition we have the task of 

 the Danaides in evidence — a perpetual filling and a perpetual emptying 

 — where the parts come and go — are elaborated and destroyed, there 

 cannot be said to exist the state of equilibrium. Taken as a whole, 

 doubtless, the sum of the functions leads to what is justly considered 

 static or normal condition, but individually not so : the whole is made 

 up of its parts, but here the parts (organs) maintain the whole. The 

 division, were the desire of peculiarity the object, might have been into 

 hematogenic or histogenic, within which category all could justly be 

 classed, and neurasthetics, into the functions of nutrition and those of 

 the nerves cranial, spinal, and sympathetic ; but the division of Bichat 

 is really in our idea the least objectionable. The book will answer 

 well for the educated man or the practitioner, for whom this survey, 

 at once condensed, accurate and excellent, will be an epitome of 

 biology ; but to the student of medicine, we much fear that it can 

 scarcely, to the exclusion of others more elementary though more 

 diffuse, be recommended as a text-book, so that a large portion of its 

 popularity may thus not be attained. Of the wood-cuts we can 

 speak in unqualified terms — many of them are from other authors — 

 some of them original and obtained by the aid of the microscope 

 applied to photography, " the process having been so far improved 

 by the author as to be rendered very available for these uses." 



Selecting one of the many chapters which merit notice, that on 

 respiration, and that portion of it especially which describes the entrance 

 of the air into the lungs, three stages are given : 1st, the filling of 

 the trachea and larger ramifications of the bronchial tubes ; 2nd. The 

 translation of the fresh air from the bronchial tubes to the ultimate 

 air cells (vesicles), accomplished by gaseous diffusion ; the 3rd stage is 

 the passage from the vesicles to the blood, through the wall of the air 

 cell (epithelium and mucous membrane) — the wall of the blood vessel 

 and the sac of the blood disc ; this involves movement through mem- 

 branes and implies condensing action. The first of these is well 

 understood, was surmised even by Empedocles, and has never been 

 misinterpreted ; the second is not so simple, is consecutive and gradual, 

 and, in his own words, is thus performed : " The carbonic acid, vapor 

 of water and excess of nitrogen, if any, that have accumulated in the 

 cells belonging to any given bronchial tree, are expelled therefrom by 



