308 THE JOURNAL OF BOTANY 



of plant-life in the Tropics, yet neither names of plants nor 

 statistics are given. Yet one more case may be cited. After 

 describing and figuring quite familiar devices for bud protection — 

 including coatings of hairs and of wax-like substances, young 

 stipules, leaf-sheaths, concave petiole-bases, peg-like ridges at the 

 bases of leaves — the author goes on to say : " In all these pro- 

 tective devices I have been able to establish the fact that when 

 they are artificially removed the buds dry and die. . . ." This 

 experimental evidence was just what was required, but how to 

 accomplish it without incidental injury to the protected parts 

 defied previous investigators. Yet Prof. Holtermann does not tell 

 us by what extremely ingenious methods he contrived to remove 

 the delicate film of wax or hairs, or the tiny pegs of Alstonia, and 

 the like. In fact, throughout the book the author fails to be con- 

 vincing. 



Though scattered about the book are interesting isolated 

 observations that seem to be new, very much of the text, even 

 the spaced text, is already well known, as would be recognized if 

 the literature were more fully cited. 



The first fifty pages deal with climate in Ceylon, and give some 

 useful quantitative statistics on transpiration. 



The next Section commences with the consideration of man- 

 grove vegetation, and a number of surprising statements are met 

 with. We are told that most botanical writers regard aqueous 

 tissue as a means of depressing transpiration, and stress is laid 

 upon the very familiar fact that in reality its function is to prevent 

 green cells from dying. But the main object seems to be to show- 

 that Schimper exaggerated the structural features devised to de- 

 press transpiration. Here the author had a chance of testing his 

 view by including detailed measurements of transpiration ; but, 

 although measurements are given (in the preceding Section) of 

 transpiration in Bhizophora and Avicmnia, they are accompanied 

 by no particulars as to temperature and atmospheric humidity, so 

 that comparison might be made with inland plants in connection 

 with which these details are, however, supplied. The statistics 

 supplied conclusively demonstrate, that in the experiment per- 

 formed transpiration was, as a matter of fact, very slow. Among 

 the curious statements designed to show the absence of histo- 

 logical protection against transpiration are the following : In 

 Bhizophora conjugata the stomata are sunken, occur only on the 

 lower face of the leaf, have strongly developed cuticular ridges, 

 but are " not xerophytic in character " ! Bruguiera gymnorhiza is 

 described as having a thick cuticle, but not so thick " dass ich, wie 

 Schimper, dies besonders betonen mochte " ! Again, in his eager 

 attack on Schimper's view that the xerophytic structure is partly 

 designed to prevent a poisonous accumulation of salt in the green 

 cells, Prof. Holtermann confidently adopts the possibly incorrect 

 and improbable assumption <4 that the cell-sap of all the cells of the 

 leaf is equally concentrated as regards common salt," and further 

 sustains his argument by informing us that no European halo- 

 phytes w T ashed by sea-water have means of depressing transpira- 



