264 Dr. Dickie on the Ovule of Euphrasia officinalis. 



minish the tendency to call in question the observations on the 

 Hemp long since recorded. Still, the action of the pollen, what- 

 ever be its nature, cannot generally be set aside. 



It will be necessary to allude briefly to the stages through 

 which the embryo passes. The first or earliest condition is that 

 of a simple cell, the germinal vesicle of Amici and others ; it may 

 be compared to the reproductive cells of some of the Algae, and 

 might be denominated with propriety the sporoid stage. The 

 appendage termed ' suspensor' is worthy of notice; it is usually 

 very highly developed in the sporoid embryo, and more so in 

 some plants than in others ; in some of the Crucifera, for example, 

 it attains considerable dimensions. I have seen an embryo of 

 Draba verna ^\^ of an inch long, with a suspensor three times 

 that length. Mr. Griffith describes the embryo in Gnetum as 

 being attached to an enormously long, tortuous, but irregularly 

 twisted cellular suspensor, its length varying from 3| to 5 inches ; 

 the whole length of the seed being about 1 inch. 



Different opinions are entertained respecting the true nature 

 of this appendage. According to Schleiden's view it is part of 

 the pollen-tube ; in the Orchidea it would seem from Amici's ob- 

 servations to be part of the embryo-sac ; he states that the part 

 of the sac which was in contact with the pollen-tube becomes 

 elongated upwards, dividing likewise into cells, which are trans- 

 parent and situated one above another, so as to form a large 

 confervoid filament ; thus traversing in the opposite direction the 

 course followed by the pollen-tube, becoming enlarged and pass- 

 ing through the orifices of the tegmen and testa, and being pro- 

 longed even as far as the placenta. According to Mohl the 

 suspensor is essentially connected with the embryo, both being 

 produced by the growth and division of the germinal vesicle, the 

 lowest cell, the embryo, growing faster than the others. In 

 Tropaolum, however, the development of the suspensor seems to 

 precede that of the embryo ; such at least is the result of Mr. 

 Wilson's observations upon that plant*. It has been already 

 stated that the embryo in its first stage may be compared to the 

 spore of an Alga ; future observations may afford greater reason 

 than at present for saying, that the sporoid embryo of some 

 phsenogamous plants germinates in situ, emitting a confervoid 

 filament, and requiring no transference to a new nidus, but find- 

 ing in the interior of the embryo-sac all the conditions neces- 

 sary to its existence and future development as a spore up to a 

 certain period. In such Algre as Vaucheria, Derbesia, &c, the 

 spores usually escape from the cell in which they are produced ; 

 being furnished with cilia they are enabled to disperse them- 

 selves abroad, after a time they become fixed, and produce a 

 * London Journal of Botany, vol. ii. p. 023. 



