146 



the winter in u ilry state, during that period; nor was it 

 until March 11th that I exposed a few of them to germinate, 

 and from the tardiness of their movements, compared with 

 others immersed afterwards, I am confirmed in my original 

 opinion, that they could not be made to grow much earlier 

 than April. The dissections of the seed last year proved of 

 considerable service, and enabled me to understand better 

 the singular appearances which present themselves. 



When the seeds have been macerated for five or six days, 

 they imbibe sufficient water to enable them to sink to the 

 bottom : previous to this they swim on the surface, and 

 when almost ready to descend, the upper end of the seed, 

 from which the embryo bursts forth, is turned downwards. 



After lying at the bottom a few days, the embryo expands 

 and bursts the inner coat of the seed, elevating its upper 

 portion, which is always circular, with a small rather thick 

 umbo at its centre. I term this part the scutelhim, * as it 

 seems destined to protect the embryo from injury while 

 breaking through the external covering, which is of a rather 

 firm texture, though much thinner in the part intended 

 for the transmission of the embryo than it is elsewhere. 

 Between this part and the apex of the inner coat of the 

 seed there is at first a considerable vacancy, and it is only 

 after the rupture of the inner coat that the embryo is 

 sufficiently swelled to arrive at the outer barrier, and force 

 open a passage. {Fig. 1.) 



At the time when that is accomplished, the embryo be- 

 comes visible, bearing on its summit the scutellum, firmly 

 attached by its centre only, to the lower lip of the cotyledon,^ 



* This is no doubt the dark spot figured in the section of the seed of Lemna 

 trisulcu, given at Jig. 13 of the plate in the Flora Londinensis, and which I have 

 there spoken of as a sort of operculum, — IV. J. H. 



f The names of the different parts are given rather from a supposed resem- 

 blance to such parts in other seeds whose structure is well known, than from 

 a full conviction of the correctness of their application. A structure so ano- 

 malous might well create doubts in the minds of the most experienced botanists. 

 — //'. J. II. 



