i 9 ig] DUPLER—TAXUS 351 



number, when viewed in longitudinal section." Coulter and 

 Land, interpreting the structures in abortive sporangia, conclude 

 that in Torreya taxijolia there is "a single hypodermal archesporial 

 cell." Miss Robertson did not get the origin of the sporogenous 

 tissue in T. California! . 



In Taxus canadensis the development follows the usual eu- 

 sporangiate method, the 4-8 (usually 5-7) archesporial initials 

 arising from the hypodermal layer of the sporophyll primordium 

 while this structure is yet quite small (fig. 23), being uniformly 

 distributed along its margin, and, dividing by periclinal walls, form 

 the primary wall cell and the primary sporogenous cell (figs. 27-29), 

 as in Torreya taxijolia (5) and most other forms. These initials are 

 first to be recognized by the size of the cells and of their nuclei 

 (figs. 23-26). One initial cell seems to be the rule, although cases 

 were found in which the archesporium consists of 2 cells (fig. 26). 



Sporogenous tissue. — The primary sporogenous cell or cells 

 soon divide periclinally (fig. 30) or anticlinally before or after 

 the division of the primary wall cell, and by successive divisions the 

 mass of the sporogenous cells is increased (figs. 31-35), the formation 

 and growth of which result in the lobed peltate structure of the 

 sporophyll, the sporangia being uniformly distributed around the 

 central axis which continues the very short stalk of the sporophyll. 

 As the tissue increases there is a corresponding growth of the epider- 

 mis and the sporangium wall (to be described later), the completion 

 of which results in the separation of the sporogenous tissue from the 

 other portion of the sporophyll (fig. 34). The tapetum is differen- 

 tiated from the peripheral layer, and the remaining sporogenous 

 mass increases in amount until the mother cell stage is reached early 

 in October, as described by Chamberlain (3) and the writer (8). 

 This has been given (6) , and even quite recently (7) , as the winter 

 condition of the microsporangium, and has frequently been quoted 

 by writers. As the author has already pointed out (8), microspore 

 formation takes place during the early part of October, collections 

 covering a number of years and from several localities in the 

 northern United States bearing out the statement that the 

 microspore is the winter condition of Taxus canadensis. Stras- 

 burger (25) found microspore formation in T. baccata taking place 



