ANATOMY AND PHYLOGENY OF TIIK CONIFERALES. 



33 



of the wood, resin canals may always be recalled as a result of injury. The disappearance 

 of resin canals and their replacement by resin cells is probably for the sake of economy 

 of carbo-hydrate material. In Pseudolarix and Tsuga even the cortical resin canals 

 disappear from all organs except the female reproductive axis, together with its append- 

 ages, and the vegetative leaf. 



5. The Abietineae are an older group than the Cupressineae, in the larger sense, 

 and are either antecedent to these or from the same ancestry. This conclusion is readied 

 from an anatomical and experimental morphological study of their organs, root, shoot, and 

 leaf. It is confirmed by the examination of the female reproductive organs and of the 

 pollen. It is further in conformity with palaeontological evidence. 



6. The Abietineae are throughout characterized by the same double leaf trace which 

 is a constant feature of the older Gymnosperms, the Lyginodendreae, the Cordaitales, the 

 Ginkgoales, and the Cycadales. This feature serves to separate them from the Cupressi- 

 neae in the larger sense, and to unite them with the Cordaitales, which they resemble in 

 other important particulars, described in the body of the memoir. 



7. The Abietineae must be regarded on comparative anatomical and morphological 

 grounds as a very ancient order of the Coniferales, and may even be the oldest living rep- 

 resentatives of this group. 



In conclusion, I wish to express my obligation to Prof. G. L. Goodale for access to 

 the specimens of wood in the economic collections of the Museum. I am indebted to my 

 father for material collected during his summer vacation. My thanks are also due to Mr. 

 George S. Shaw, former chairman of the visiting committee to the Museum, and through 

 him to Prof. C. S. Sargent and Mr. Jackson Dawson of the Arnold arboretum of Harvard 

 university, and to Mr. Walter Hunnewell, the present owner of the Hunnewell pinetum. 

 But for the kindness of Mr. Shaw and those he has interested in my needs, this work 

 could scarcely have been carried to a conclusion. A considerable amount of valuable 

 material has reached me from the authorities of the Royal gardens, Kew, England, for 

 which I likewise wish to offer my sincere thanks. 



Phanerogamic Laboratories 



of Harvard University. 



