BOOKS AND CURRENT LITERATURE 



Physiological Problems of Photosynthesis. — A recent paper 1 

 presents the results of a comparative study of the photosynthetic 

 activities of lowland (276 meters) and alpine (1709 meters and 2456 

 meters) plants. This paper is interesting not only because of the 

 decided differences that were found in the behavior of plants from these 

 two types of habitat but perhaps even more because it leaves the reader 

 with the conviction that, in spite of the assurance with which the 

 subject of photosynthesis is usually presented, very little is really known 

 regarding this fundamentally important problem of plant physiology. 

 In spite of the more general interest in the purely chemical aspects 

 we are as much in the dark regarding the chemical steps in the process 

 as we were in 1870 when Baeyer proposed the formaldehyde hypothesis. 

 Willstatter's researches have cleared up much that was confusing 

 regarding the organic chemistry of the leaf pigments but they have 

 done practically nothing directly to solve the more important physio- 

 logical problems except to give the physiologist tools with which to 

 work. Much excellent investigation has been carried on by Blackman 

 and his co-workers upon these latter problems but we are far from know- 

 ing even the conditions without and within the plant that are usually 

 influential. 



Our ignorance of the measurements that should be made upon the 

 plant and its surroundings in a photosynthetic research is well illus- 

 trated by the author's discussions of the problems encountered. These 

 include: the amount of chlorophyll in the leaves; diurnal variations 

 in the amount of chlorophyll; the use of fresh weight or dry weight of 

 leaves as the unit of reference in stating the amount of chlorophyll; 

 the ecological character of the plants (the author used chiefly "meadow 

 plants:" Anthyllis Vulneraria, Bellis perennis, Primula farinosa, Taraxi- 

 cum officinale; "plants of the snow ravines:" Primula integrifolia, 

 Soldanello, alpina); anatomical characteristics of the plants; where and 

 how to take the temperature; methods of measuring the assimilate; 



x Henrioi, Marguerite, Chlorophyllgehalt unci Kohlensaure — Assimilation bei 

 Alpen — unci Ebenenpflanzen. Verhand. Naturforsch. Gesell. Basel. 30: 43- 

 136. 1918. 



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