272 Mr. Griffith on the Ainbrosinia ciliata of Roxburgh. 



processes only. They are most abundant towards the apices of these, espe- 

 cially on the portion which corresponds to the lamina of the perfect leaf, and 

 are perhaps altogether wanting towards or near their dilated bases. The 

 cells of the cotyledon as well as of the processes of the plumula, in an early 

 stage of their development, abound in active molecules, which have both in 

 and out of the containing cells an exceedingly rapid oscillatory motion. It 

 is obvious, from the universal presence of these corpuscles during the forma- 

 tion of tissue, that they play an important part in this most obscure process. 



The processes of the plumula remain for some time entirely cellular ; at an 

 early period they have a close resemblance to the very minute leaves which 

 exist in the axillae of the convolute unexpanded leaves. 



With regard to the elongated cellular tissue or hairs of the surface of the 

 placentae, which exist in such abundance in the ovarium at the time of 

 impregnation, I have merely to add that their formation appears to be subse- 

 quent to the first appearance of the testa. They have attained a considerable 

 size in those placentae the ovula of which have the nucleus half-exserted. 

 They contain active molecules, but I have not been able to detect any motion 

 of ascent or descent. They do not disappear in the mature fruit, but are 

 visible, arranged irregularly about the bases of the seeds. 



About the time of dehiscence, or before this, on immersing the seeds in 

 water for a short time, spontaneous separation of the cotyledon will have 

 generally taken place about the apex of the nucleus. The truncated base of 

 the cotyledon, after this has separated, will be seen occupying the depressed 

 centre of the plane inferior surface of the axis. The testa will frequently be 

 found ruptured. Yet this can scarcely be, as Roxburgh seems to think, 

 called germination, which in this singular plant cannot be said to take place 

 until the radicle has elongated and the innermost convolute processes have 

 become expanded. The axis contains the rudiments of additional radicles, 

 which, from their mode of development, may truly be said to be exserted. 

 This I have never seen to take place before germination, as I conceive it to 

 be limited. 



I shall now pass to the consideration of the anomalous points of structure 

 of the ovulum, particularly of those of which explanations have suggested 

 themselves during the course of my inquiry. 



