35° BOTANICAL GAZETTE [xovember 



but the primordia of the sporophylls did not begin to appear until 

 August. The greater meristematic activity in some regions of this 

 rounded apex than in others marks the position of the primordia 

 of the sporophylls. These soon become rounded lobes above the 

 general surface (figs. 5, 6). The nature of the growth of the 

 primordium would indicate that it arises from a group of meriste- 

 matic cells rather than from a definite initial; at least no defined 

 sporophyll initial could be recognized. 



The sporophylls are probably spirally arranged, although this 

 is somewhat indefinite, and indications were found in a few cases 

 that they may arise in acropetal succession (fig. 5) ; but if this is the 

 case it is very soon obscured in the uniform development of the 

 primordia as the sporophylls develop, no trace of the axis apex 

 being recognizable after the very early beginnings of the sporo- 

 phylls. The early development of the primordium is uniform in all 

 directions from its central axis, at least until the differentiation of 

 the archesporial initials takes place. The strobilus in this stage 

 shows a series of rounded sporophyll primordia (figs. 5, 6, 23). The 

 later development of the sporophyll is so intimately bound up with 

 the development of the sporangia as to best be described in con- 

 nection with them. In fact, the development of the sporangia 

 determines the shape and character of the sporophyll, as aside from 

 the sporangia the sporophyll consists of practically nothing 

 excepting the short central axis and the epidermis. 



MICROSPORANGIUM 



Archesporial initials. — Hofmeister (ii) seems to have been 

 the first to publish with reference to the microsporangium of 

 conifers, reporting the spore mother cell stage as being reached in 

 Pinus maritima in November. Goebel (9) traced the arche- 

 sporium of Pinus to a single hypodermal cell, and claimed a similar 

 origin for the archesporium of Thuja. His most important observa- 

 tion on this point was that the development of the microsporangium 

 is like that of the eusporangiate ferns. Coker (4) in Taxodium 

 distichum, and Nichols (17) in Juniperus communis var. depressa, 

 also found a hypodermal origin of the archesporium, in the 

 hitler case consisting of "a plate of radially elongated cells, 4-6 in 



