Dr. Dickie on the Ovule of Euphrasia officinalis. 265 



plant like the parent. We may suppose that such change of cir- 

 cumstances is necessary to their proper development ; the very fact 

 of number alone would in certain cases be an obstacle to their 

 growth in their original situation. In some instances however they 

 do germinate in situ ; these form the exception and not the rule. 

 The sporoid embryo is usually solitary {Citrus, Conifercs, &c. pre- 

 sent exceptions) ; it does not require to change its place, but be- 

 gins to germinate in situ, producing a confervoid filament, the 

 embryo suspensor, which is usually directed towards the apex of 

 the nucleus. But it may be objected to this idea, that spores do 

 not germinate from any special fixed point ; this however is not 

 proved, for who has yet demonstrated that they have not a fixed 

 point for the origin of the thread they produce ? Sometimes 

 however the suspensor is not directed towards the micropyle, 

 but away from it ; Gasparrini has observed this in Citrus, and 

 Griffith observed that in Osyris the part corresponding to the 

 suspensor has a direction quite opposed to the point reached by 

 the pollen-tube. In the ovule of Euphrasia, the peculiarities of 

 which have been already described, it is probable that the tubu- 

 lar filamentous appendage which protrudes from the apex of the 

 embryo-sac is a prolongation of the terminal joint of the sus- 

 pensor ; at all events it cannot be derived from the pollen for 

 reasons already given ; at the same time it is not denied that the 

 pollen-tube may reach and come in contact with the apex of the 

 sac, though I have hitherto failed in detecting its presence. In 

 a former communication an opinion was expressed that the 

 jointed appendage of the embryo in the Orchidece is no part of the 

 pollen-tube, as supposed by Schlciden, but a process from the 

 embryo itself; it was also added, that a tubular prolongation of its 

 terminal joint might account for the presence of those tubes so 

 abundant upon the placenta, and which had been by most ob- 

 servers considered to be derived from the pollen. From the 

 observations of Mohl and others it would appear that the state- 

 ment alluded to was only partially correct, their observations 

 having confirmed the first part, but shown the second to be er- 

 roneous. For reasons already mentioned it would be premature 

 to state that the production of the confervoid filament or sus- 

 pensor, in other words, the germination of the sporoid embryo, 

 forms the second stage of its development. 



This stage appears to be quite independent of the action of 

 the poUen. Mirbel and Spach in 1839* demonstrated that 

 the first appearance of the embryo, the germinal vesicle, called 

 hy them primary utricle, precedes the application of the poUen. 

 Tliis early formation of the germinal vesicle, the first outline 

 of the embryo, was proved by them in a large number of 



♦ Report by M. Giraud in ' Annals of Nat. Hist.' vol. v. 

 Ann. if Mag. N. Hist. Ser.2. Vol.i. 18 



