Experimental Investigations on the Genus Drimys. 
BY 
E XPERIMENTAL investigation has come prominently into the fore- 
ground in many lines of botanical work in recent years. In no case, 
perhaps, is its value so clear as in the case of the Conifers, which present 
the great advantage of a long anatomical history displayed in the strata, by 
means of which experimental results may be controlled. An interesting 
general result which has been derived from united palaeobotanical and 
experimental study in the case of the Conifers is that the more simply 
organized subtribes of the group are derived from ancestors with more 
complex anatomical structures. One of us pointed out a number of years 
ago, 1 ' 2 that in the genus Sequoia and in those genera of the Abietineae 
without normal resin canals in the secondary wood {Abies, Tsuga , Pseudo- 
larix , and Cedrus), resin canals reappear as a consequence of injury. This 
reappearance of secretory canals as a phenomenon of injury is particularly 
significant because these structures are found to a large degree normally in 
the more conservative regions of the genera named. Later investigations 
have shown further that the rays of certain Conifers may be modified 
experimentally in an interesting way. First, in the genus Cunninghamia 3 
it was demonstrated that a frequent result of injuries was the appearance 
of marginal ray tracheides, such as are characteristic of the pine-like 
1 Jeffrey, E. C. : The Comparative Anatomy of the Coniferales. I. The genus Sequoia. 
Mem. Boston Soc. Hist., vol. v, 1903, pp. 441-59, Pis. 68-71. 
2 Jeffrey, E. C. : The Comparative Anatomy of the Coniferales. II. The Abietineae. Mem. 
Boston Soc. Nat. Hist., vol. vi, 1904, pp. 1-37, Pis. 1-7. 
3 Jeffrey, E. C. : Traumatic Ray Tracheides in Cunninghamia sinensis. Ann. Bot., vol. xxii, 
1908, pp. 593-602, PI. XXXI. 
[Annals of Botany, Vol. XXX. No. CXIX. July, 1916.] 
