628 MICROSCOPIC FORMS OF VEGETABLE LIFE-THALLOPHYTES 



section is made through one of the flattened conceptacles of F. platy- 

 carpus, its interior is seen to be a nearly globular cavity (fig. 470), 

 lined with hairs, some of which are greatly elongated, so as to 

 project through the pore by which the cavity opens on the surface. 

 Among these are to be distinguished, towards the period of their 

 maturity, certain filaments (fig. 471, A), the antherids, whose 

 granular contents acquire an orange hue, and gradually shape 

 themselves into oval bodies (B), each with an orange -coloured spot 

 and two vibratile cilia of unequal length, placed laterally, which, 

 when discharged by the rupture of the containing cell, have for a 



time a rapid, undulatory 

 motion whereby these 

 antherozoids are diffused 

 through the surround- 

 ing liquid. Lying amidst 

 the mass of hairs, near 

 the walls of the cavity, 

 are seen (fig. 470) 

 numerous dark pear- 

 shaped bodies, which are 

 the oogones, or parent- 

 cells of the oospheres. 

 Each of these oogones 

 gives origin, by binary 

 subdivision, to a cluster 

 of eight ' germ-cells ' or 

 oospheres ; and these 

 are liberated from their 

 envelopes before the act 

 of fertilisation takes 

 place. This act consists 

 in the swarming of the 

 antherozoids over the 

 surface of the oospheres, 

 to which they communi- 

 cate a rotatory motion 

 by the vibration of their 

 own cilia. In the herm- 



FIG. 470. Vertical section of conceptacle of Fucus aphrodite Fuel this takes 

 platy corpus (lined with filaments, , among which lie lace w j t hi n the COn- 

 the antheridial cells and the oogones containing * 



oospheres. ceptacles, so that the 



oospheres do not make 



their exit from the cavity until after they have been fecundated ; 

 but in the monoecious and dioecious species each kind of conceptacle 

 separately discharges its contents, which come into contact on their 

 exterior. The antheridial cells are usually ejected entire, but soon 

 rupture so as to give exit to the antherozoids ; and the oogones also 

 discharge their oospheres, which, meeting with antherozoids, are 

 fecundated by them. The fertilised odspores soon acquire a new and 

 firm envelope ; and, under favourable circumstances, they speedily 

 begin to develop themselves into new plants. The first change is 



