504 BOTANICAL GAZETTE [june 



can be found, and that there is no ground for Van Tieghem's view. 

 Magnus (18), pointing out the cauline origin of the ovule in Naias, 

 spoke of it being similar to the situation in Taxus, in which he 

 regarded the ovule as terminal. Later workers have more generally 

 accepted the terminal nature of the structure. Celakovsky (8) 

 held that the sporangium is terminal to the axis. Worsdell (38) 

 accepted and championed this view, stating that "anatomy points 

 clearly to the fact that no axial foliar appendage of any kind exists 

 upon which the sporangium is inserted, the cylinder of the axis 

 being directly continuous into the base of the sporangium." 

 Jager (15) speaks of the nucellus in T. baccata being formed by the 

 vegetative tip of the secondary shoot. Miss Aase (i), in a recent 

 study of this problem, points out that the vascular supply to the 

 ovule is "contrary to what should be expected" for an axillary 

 structure. She also suggests the possibility of a fusion of sporo- 

 phylls to form a single structure. 



For a solution of the problem two groups of facts can be used 

 directly, the origin and development of the ovule, and its vascular 

 supply; the latter will be treated in connection with the vascular 

 features of the secondary shoot as a whole. There are no known 

 abnormalities with which one can compare the normal situation. 

 Torreya apparently presents a similar situation, and thus gives no 

 additional line of evidence. 



Origin of ovule.— The first indication of the ovular nature 

 of the end of the shoot is the beginning of the integument as a ring 

 around the tip of the axis (figs. 37, 38), and the axis tip itself becom- 

 ing the nucellus, as claimed by both Strasburger (36) and Jager 

 (15) for T. baccata. There is nothing in the position of the ovule 

 to indicate that it is a lateral structure, and so far as its ontogenetic 

 origin gives a clue one must conclude that the ovule is strictly 

 terminal, cauline in origin, and unrelated to any of the scales. If 

 the scales represent sterile sporophylls phylogenetically, as is 

 most probable, their sporophyll character has been completely 

 abandoned and the axis itself becomes the sporangium, as in some 

 of the angiosperms, where cauline ovules are not uncommon. 

 That the vascular features sustain this view will be indicated 

 later. 



