Nov., 1919] Proliferative Power of Pinus sp. 23 



Some opportunity was afforded to observe in the vicinity 

 the effect of the various poison gases, (phosgene, chlorine, 

 "mustard," etc.), on the two types of trees, angiosperms and 

 gymnosperms, in a portion of the proving ground where there 

 had been extensive artillery firing. Here the former seemed 

 more in luck, proliferation seemed to be reduced in the conifers 

 and these trees, although scarcely damaged by shell fragments, 

 apparently were scarcely living and had a comparatively 

 greater number of dead branches. A possible reason is the greater 

 ease of aeration of leaves in the angiosperm, which the thick 

 bushy leaves of the conifers seems to inhibit. The fact that the 

 whole tree seemed to suffer when under such conditions, would 

 seem to indicate that the effects of these substances is by no 

 means localized, but would seem to exist throughout the tree. 

 While dead branches in the other type of tree were not uncom- 

 mon, yet the impression was gained that on the whole they had 

 suffered less. 



Dr. O. E. Jennings, Curator of Botany, Carnegie Museum, 

 has been kind enough to make certain comments on this data, 

 which I have combined in the above. 



Hollins College. 



