REVIEWS 635 



for a certain period of time. Ag-ain a slight curvature may accelerate 

 the growth on the upper side of a dicotyledonous stem, whereas a 

 more pronounced bend may produce excentricity upon the under side 

 or inhibit the growth of- both the upper and lower sides and lead to 

 lateral eccentricity. 



In the fifth and concluding section of the volume, Jaccard elaborates 

 the following hypothesis : "The morphological characters common to 

 all trees are determined (1) by the polarity of their organs, that is to 

 say, by their tendency to grow most rapidly in a vertical direction, 

 and (2) by the modifications which the exigencies of nutrition and the 

 action of external forces (gravity, heat, light) impress upon the polar- 

 ity. These modifications manifest themselves through the osmotic 

 force of cells which engenders, on the one hand, two circulatory cur- 

 rents (the ascending sap and descending current of elaborated sub- 

 stances) and, on the other hand, mechanical strains and stresses (pres- 

 sure of turgescence) capable of influencing the form of cells. In gen- 

 eral, such variations in gross form and anatomical structure — as may 

 be observed at different levels in the concentric, vertical axes of trees 

 — are determined by the physical conditions of the transpiration stream 

 and the flow of elaborated sap. On the contrary, the anatomical differ- 

 entiation and variations in transverse sections, which are concomitants 

 of the excentric growth of inclined or horizontal branches, are due to 

 mechanical forces engendered by the unequally rapid growth of the 

 antagonistic sides of these organs, under the asymmetrical influence 

 of gravity and light." I. W. Bailey. 



Nczv Zealand Forestry, Part I. Kauri Forests and Forests of the 

 North and Forest Management. By D. E. Hutchins, I. F. S., li>19. 



The pressure for "popular" writing, to stir up an interest in forest 

 matters, is by no means confined to the United States. It is, however, 

 to be regretted that a man of the reputation and ability of Mr. Hutch- 

 ins has found it necessary to publish what is obviously a hastily writ- 

 ten book on his observations in the forests of New Zealand, with- 

 out specific data and without even verifying data applicable to other 

 countries to which he refers. It can not be doubted that conditions in 

 New Zealand in 1!)1.S called for radical action and doubtless Mr. 

 Hutchins' book on the Kauri forests served a very useful purpose in 

 securing the progressive action which has been taken since it was 

 written. It is, however, a curious mixture of appeals to local nride 



