394 BOOKS AND CURRENT LITERATURE 



a tacit dismissal of the osmotic theory of Pfeffer and De Vries, the lipoid 

 membrane theory of Overton, the mosaic thoery of Nathansohn, and 

 the pressure theory of Pfeffer and his students. All of these theories 

 depend for their operation, upon the presence of a membrane through 

 which water and the dissolved substances pass. Difficulty arises when 

 one attempts to explain by these theories, how both water and dissolved 

 substances move into the cell at the same time or out at the same time, 

 or in opposite directions, either into the cell or out of the cell at the same 

 time, yet this must be possible within living cells. By the theory 

 which regards the protoplast as a colloid-chemical complex, there is no 

 need for membranes about the cells. This colloid complex cannot 

 only absorb and secrete water, but it can absorb and secrete any dis- 

 solved substance at the same time, the two processes being directed 

 either in the same or opposite directions. The laws governing hydra- 

 tion and dehydration of lyophilic colloids then govern their absorp- 

 tion and secretion. The differences in concentration within and without 

 the cell can thus be accounted for by differences in solubility, differences 

 in adsorption, and differences in chemical constitution. 



The problem of oedema is regarded as dependent upon an increased 

 or heightened hydration of the body colloids and the cause of which in- 

 crease exists within the tissues themselves. This increased hydration, 

 he maintains, is caused by the accumulation of .acids within the tissues, 

 brought about either through their abnormal production, or through 

 their inadequate removal, though some of it may be due to the produc- 

 tion or accumulation of substances of the type or urea, pyridin, certain 

 amins, etc., which hydrate colloids as do acids, or even to the conver- 

 sion of colloids having little capacity for water to those having a greater 

 hydrophylic capacity. The bearing of the problem of oedema in ani- 

 mals to such states in plants as are described as overgrowths, excres- 

 cences, galls, cankers, intumescences, crown gall, knots, etc .are not far to 

 be sought. Furthermore, the author 's experimental procedure on oede- 

 ma is such that it could in many cases be duplicated in work of instruc- 

 tion in the classroom and laboratory. 



The studies in secretion are for the most part concerned with the kid- 

 ney but here again many related problems suggest themselves and both 

 the investigator and the teacher will find a lively interest in Dr. Fischer 's 

 treatment of the fundamentals of the process. Such interesting vital 

 questions as the reason for a decreased urinary output following anaes- 

 why blood remains in the vessels, are all included in the problem of se- 

 cretion and are presented with a body of clinical and experimental data, 



Frederick A. Wolf. 



