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, Conifer at, &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 Osijris 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 Schleiden, 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 pollen. Mirbel and Spach in 1839* demonstrated that 
the first appearance of the embryo, the germinal vesicle, called 
by them primary utricle, precedes the application of the pollen. 
This 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. ^ Mag. N. Hist. Ser. 2. Vol. i. 18 
