146 BOOKS AND CURRENT LITERATURE 



lakes and marshes. This list is sufficient evidence of the complexity 

 of the vegetation and the space of this review is quite inadequate to 

 depict even the important details of the paper. 



This paper should be read by all students of vegetation, and is to be 

 commended for its clearness, the evident accuracy of the plant lists 

 (including bryophytes and lichens), and the admirable discussion of 

 climatic and edaphic conditions. — E. N. Transeau. 



Physiology of the Mangrove. — The results of two summers of 

 laboratory and field work on the red mangrove {Rhizophora mangle) 

 have been published by Dr. H. H. M. Bowman of Heidelberg University, 

 Tiffin, Ohio. 1 The work was clone in Florida under the auspices of 

 the Department of Marine Biology of the Carnegie Institution. The 

 morphological and histological characteristics of stem, root, leaf and 

 flower are described in detail, and the copious literature relating to 

 this tree is reviewed in connection with each topic. The most original 

 features of Bowman's work have to do with the transpiration of seed- 

 lings and the biochemistry of the hypocotyl. 



The seedlings used for transpiration work were placed in water, in 

 wet sand or in mud, the water being changed daily. The readings 

 were made by means of cobalt chloride paper, dried in a desiccator and 

 applied with an appropriate clip. No temperature readings were taken, 

 although of great importance in calibrating results by this method, 

 and the author made no attempt to render his results comparable with 

 those for other plants by availing himself of the method of standardizing 

 the paper to a water surface, as described by Livingston in 1913.' 2 Seed- 

 lings were placed in rain water, in five mixtures of rain and sea water — 

 with increasing percentages of the latter — and in pure sea water. The 

 times required for the same color change in the cobalt chloride paper 

 ranged from 1.6 minutes in rain water, through progressive^ increasing 

 periods for the mixtures to 4.1 minutes for sea water, indicating that 

 transpiration is over two and a half times as great in fresh water as in 

 sea water. Determinations were made in sun and in shade, as well 

 as in different substrata, but as separate results for the various series 

 are not given the question arises as to why they were made. By use 

 of the same method the transpiration through the lenticels of the crop 



1 Bowman, H. H. M. Ecology and physiology of the red mangrove. Proc. 

 Amer. Phil. Soc. 56: 589-672, pis. 4-9, 1917. 



2 Livingston, B. E. The resistance offered by leaves to transpirational water 

 loss. The Plant World 16: 1-35, 1913. 



