564 DR. M. T. MASTERS: GENERAL VIEW 
(Pl. 20. fig. 1). The branching or otherwise of the fibro-vascular 
bundle is a more important “ character” than that furnished by 
the position of the resin-canals. At the same time it may be 
pointed out, as a fact of some possible significance as regards 
the phylogeny of the genus, that in the cotyledons and in the 
primordial leaves the fibro-vascular bundles may be unbranched 
(Pl. 22. fig. 8; Pl. 23. fig. 9), whilst in the adult foliage they 
may be branched. So, also, the resin-canals may in the primordial 
leaves be marginal, as in P. Lambertiana (PI. 23. fig. 9), whilst 
in the adult foliage they are generaily median. 
M. Casimir de Candolle, however, in relation to the juvenile 
character of the leaves on adventitious shoots, says that the 
“caractére juvénile rentre dans la loi du développement indi- 
viduel de la plante et il fait partie de "ensemble des caractéres 
normaux de chaque espéce. Il ne faut donc pas considérer 
comme un cas de variabilité régressive de l’espéce, et il n’y a 
pas lieu de lui attribuer, ainsi que l’on a fait quelquefois 
Yimportance d’une indication phylogénétique”’ (Archiv. des 
Sciences physiques et naturelles, t. xvi. July 1903, p. 68). In 
what way we are to distinguish between what is peculiar to 
the individual, and what is of genealogical significance, is not 
apparent. 
In the following notes I have availed myself of the information 
published by my predecessors, and of the incidental observations 
of Van Tieghem, Bertrand, MacNab, and others to whom 
reference is made in the course of this paper. It may be here 
pointed out that a valuable character has been hitherto almost 
entirely overlooked, or not accorded the importance which it 
deserves. I allude to the number and characteristics of the 
cells constituting the endoderm-layer. I have not examined 
this layer in all the species, nor in many specimens of each 
species, but in a number sufficient to enable me to form a high 
estimate of its value for classificatory purposes. 
I have repeatedly examined the leaf-structure in the majority 
of the species, both in a living state and when dried; and 1 
gratefully acknowledge the assistance I have had from the 
beautiful specimens of the American species prepared by 
Mr. King. These were described and illustrated by Messrs. 
Coulter and Rose *. Specimens have also been made for me 
* “Synopsis of North-American Pines based upon Leaf-Anatomy,” Botanical 
Gazette (1886), p. 256. See also Bastin and Trimble, ‘A Contribution to the 
