THE AMERICAN NATURALIST. XXXVIII. 



vided with simple pits, though often few in number, and this 

 feature serves to a large extent, to assist in their differentiation 

 from adjacent tracheids of similar form (Figs. 36 & 38). It 

 nevertheless not infrequently happens that in transitional forms, 

 such as are met with in Sequoia senipcrvirois {V\g. 37^), 

 bordered pits occur on the lateral walls. 



The resin is in all cases massive and often very abundant. 



In such genera as Taxodium or Sequoia it completely fills the 

 entire cell' cavity (Figs. 39 & 40), but in Larix, Tsuga and 

 Pseudotsuga it takes the form of a peripheral layer in immediate 

 contact with the inner face of the cell wall (Fig. 42). The 

 reduction thus indicated is, in some species, carried to such an 



