VERGLEICHENDE PHYSIOLOGIE 67 



of the achievements in other branches. An attempt is here made 

 to discuss the problems of the fundamental processes of life in the 

 light of the results obtained from all the various branches of bio- 

 logical study. It is clear that the task is no light one, for the 

 field to be surveyed is of great extent, but the author must be con- 

 gratulated on the laborious care v^ith v^hich the most pregnant 

 physiological results have been collected from biological literature 

 generally, and the skilful way in v^hich they have been combined 

 to elucidate the various problems. 



The first chapter deals with the physical and chemical nature 

 of protoplasm ; then the important question of metabolism is 

 brought under survey, and a sharp distinction is made between 

 Betriebstoffwechsel and Baustoffwechsel, which roughly corre- 

 spond to our constructive and destructive metabolism. In this 

 chapter respiration in plants and animals is dealt with in a most 

 illuminating way, and the variety of materials consumed in this 

 process is well brought out. When one considers that such 

 diverse substances as hydrogen, methane, ammonium salts, 

 nitrites, sulphur, hydrogen sulphide, thiosulphates, and ferrous 

 salts can all be oxidized in respiration, Pfltiger's conception of 

 that process as a combustion of the protoplasm itself becomes 

 hardly tenable. It may be noted that in dealing with fermenta- 

 tion the work of Potter (Proc. Eoy. Soc. 80, 1908) is overlooked, 

 for the statement is made that no organism has yet been found 

 capable of acting on carbon itself. 



In the third chapter the processes of nutrition are passed in 

 review, the phyto-synthetic assimilation of green plants being 

 first considered. The different types of nutrition are discussed, 

 and the unsatisfactory nature of the distinction between auto- 

 trophism and heterotrophism is pointed out. The disputed 

 question of the mode of nutrition of aquatic animals is fully 

 discussed. Piitter naturally supports the view, which he first 

 put forward some years ago, that the vegetable life of the water is 

 not sufficient to supply the needs of the animal life. He brings 

 forward strong evidence that many aquatic animals absorb all, or 

 a major portion of, their nutriment from dissolved organic sub- 

 stances in the water. In the case of one of the Da^hnidcB 

 (water-fleas) the capacity to live for some time and develop in 

 aquarium-water containing no solid material has been definitely 

 shown. In later chapters the exchange of material, the conditions 

 of life, the conversion of energy in the organism are considered, 

 and finally the phenomena of irritability and the nervous system 

 in general. The author shows a thorough grasp of problems in 

 plant physiology, due largely, no doubt, to Pfeffer's stimulating 

 work which Dr. Putter acknowledges to have made a lasting 

 impression on his outlook on biology. 



The book can be confidently recommended to botanists as a 

 work in which the zoological aspects of physiological problems 

 are combined with the botanical in a most illuminating way. 



V. H. Blackman. 



