192 TRANS. ST. LOUIS ACAD. SCIENCE. 



ascending axis, nourished by the food contained in the cotyle- 

 dons ; these become exhausted and rot away about the end of 

 the first season, while the radicle about the same time swells up, 

 evidently absorbing part of the matter contained in them and 

 thus laying up a store of food for the next season. 



The process in ^. virens is essentially the same ; it differs 

 somewhat in that the connate stalk of the cotyledons remains 

 more slender, but elongates more, mostly to the extent of one inch 

 or even more ; the caulicle and upper part of the root swells up 

 at once, while the developing plumule forces its way up through 

 a slit in the base of the stalk. It seems that the danger of losing 

 connection with the storehouse of the cotyledonous mass through 

 the long and slender passage of the stalk, necessitates the trans- 

 fer of the food-matter to a nearer and safer place of deposit. But 

 why, it maybe asked, is the connection so much longer and more 

 slender than in other oaks? At all events it suffices, as long as 

 it is fresh and unimpaired, to carry over in a very short time 

 the starchy and sweet contents from the cotyledons to the tuber ; 

 and before the ascending axis is an inch high and bears as yet 

 only a few minute bracts, the tuber is already forming and it soon 

 reaches the size of the cotyledons themselves ; it is, however,, 

 longer and more slender, of a fusiform shape, about three to four 

 lines thick and one to two inches long, attenuated below into the 

 long tap-root. 



The whole process is similar to the germination of the cucurbi- 

 taceous Megarrhiza of California, so beautifully illustrated by 

 Gray in his Structural Botany ; with this difference, that the 

 cotyledons in that plant are raised above the ground, while in 

 ours they remain hypogaeous, and that the stalk is even longer, 

 and is, together with the cotyledons, readily separable into its two 

 component parts. In both plants a tuber forms at once by the 

 transfer of the food-matter from the cotyledons to the radicle ; in 

 the herbaceous Megarrhiza the tuber becomes a permanent organ 

 of immense size, while in the arboreous live-oak it is finally 

 merged in the root. 



