622 THE GARDENER. [Nov. 



future plant. Even at this period, after the radicle has become a per- 

 fect root, the plant, as Sennebier ascertained by experiment, ceases to 

 germinate if the cotyledons be cut off. They are still, then, absolutely 

 necessary for the vegetation of the plant. The cotyledons now assume 

 the appearance of leaves, and appear above the ground, forming what 

 are called cotyledon-leaves of the plant. After this the plumule gradu- 

 ally increases in size, rises out of the earth, and expands itself into 

 branches and leaves. The cotyledon-leaves soon after this drop off 

 and decay. 



As it does not appear that there is any communication between 

 the cotyledons and the plumule, we must infer that the nourishment 

 that the plumule obtains must pass into it from the radicle ; and 

 accordingly, we see that the plumule does not begin to vegetate until 

 some time after the radicle has made a little progress. Since the plant 

 ceases to vegetate, even after the radicle has been converted into a 

 root, if the cotyledons be removed before the plumule is developed, it 

 follows that the radicle is insufficient of itself to carry on the processes 

 of vegetation, and that the cotyledons still continue to perform a part 

 — and that is, they prepare food for the nourishment of the plant. 

 When the young plant assumes the form of cotyledon-leaves, it is very 

 evident that the nourishment, which was originally laid up in them for 

 the support of the embryo plant, is exhausted, yet they still continue 

 as necessary as ever. They must therefore receive the nourishment 

 which is imbibed by the roots : they must produce some changes on it 

 — render it suitable for the purposes of vegetation — and then send it 

 back again to be transmitted to the plumule. After a plumule has ac- 

 quired a certain size, which must at least be a line, if the cotyledons 

 be cut off, the plant, both Bonnet and Sennebier ascertained by experi- 

 ments, does not cease to vegetate, but it continues always a mere pigmy 

 — its size when compared with that of a plant whose cotyledons are 

 allowed to remain, being only as 2 to 7. When the plumule has ex- 

 panded completely into leaves, the cotyledons maybe removed without 

 injuring the plant, and they very soon die of themselves. It appears, 

 then, that this new office of the cotyledons is afterwards performed by 

 that part of the plant which is above ground. For a fuller explana- 

 tion, and various modes of germination, see the 'Gardener' of 

 September 1880, page 414. 



The embryo is usually solitary in the seed, but occasionally there 

 are two or several. 



When several embryos are produced within a single seed, it some- 

 times happens that two of these embryos grow together, in which case 

 a production analogous to animal dicephalous monsters is formed. 



The number of cotyledons varies from one to several ; commonly 

 two, in which case they are mostly opposite : E.c. Pea, Bean, (fee. 



W. Egberts. 

 {To he continued.) 



