~ 
; 
858 REPRODUCTION OF THE GYMNOSPERMIA. 
cells of the second layer, so that each is separated from the 
membrane of the primary embryo-sac by one cell (jig. 1162, a). 
These corpusculu, as they were called by Robert Brown, their 
discoverer, are very much lke the archegonia in the internal 
prothallial structure of Selagiiella. After a time the secondary 
embryo-sacs divide into an upper or neck-cell, and a lower or 
central cell containing the oosphere. The neck-cell speedily 
divides and subdivides, to form the rosette which surmounts 
the central cell. In the upper part of this latter is then formed, 
Frag. 1162. 
Fig. 1162. Development of the embryo in a species of Pinus, (After Henfrey.) 
A. Upper part of the embryo-sac, with two secondary embryo-saes, cor- 
puscula, or archegonia. B. The same, more advanced. p/. Pollen-tube 
in the canal leading down to the corpuscula. a. Germinal corpuscles at 
the base of the secondary embryo-sac. FE, F,G. Successive stages of de- 
veloy ment cf germinal corpuscles,ain B. Cc. Four cellular filaments or 
suspenso7's, Which are developed from the germinal corpuscles after im- 
pregnation; at H, is shown an earlier stage. D. One of these suspensors, 
with the embryo (em) at its apex. 
from subdivision of the nucleus, a very delicate cell, which is 
called the canal-cell. The mature corpuscle therefore consists of 
a large central cell surmounted by arosette of small cells placed — 
immediately beneath the wall of the primary embryo-sac, or 
separated from it by a funnel-shaped space.’ 
The process of fertilisation takes place as follows: ‘ After 
the contact of the pollen with the micropyle of the ovule, the 
pollen-tube, after remaining passive for a variable space of 
time, takes an active growth, traverses the endosperm, and 
arrives at the embryo-sac by the time the corpuscles are de- 
veloped. It penetrates the wall of the embryo-sac, enters into 
and dilates the funnel-shaped space just mentioned, passes 
down between the cells of the rosette, pushing them on one side 
(Taxaceze, Cupressez), or causing their absorption and disap- 
pearance (Abietez) as well as that of the canal-cell, and finally 
penetrates into the cavity of the canal-cell. The changes which 
