350 MICROSCOPIC STRUCTURE OF HIGHER CEYPTOGAMIA. 



FiQ. 135. 



their escape by a passage that opens for them at the summit of 

 the antheridium. The antheridia are generally surrounded by a 



cluster of hair-like fila- 

 ments, composed of cells 

 joined together (Fig. 134, 

 a), and called "paraphy- 

 ses. " The archegonia bear 

 a general resemblance to 

 those of Marchantia (Fig. 

 131) ; and there is every 

 reason to believe that the 

 fertilization of their con- 

 tained germ-cells is ac- 

 complished in the manner 

 already described ; for 

 antherozoids have been 

 observed swimmingabout 

 around the archegonia 

 within their involucrum,' 

 and the evolution of cap- 

 sules from archegonia has 

 been ascertained not to 

 take place in those Mosses 

 which bear the two sets 

 of organs on separate in- 

 dividuals, unless an an- 

 theridial plant be in the 

 neighborhood. The fer- 

 tilized embryonal cell 

 becomes gradually deve- 

 loped by cell division into 

 a conical body elevated 

 upon a stalk ; and this at 

 length tears across the 

 walls of the flask-shaped 

 archegonium by a circu- 

 lar fissure, carrying the 

 higher part upwards as a 

 ealyptra or hood (Fig. 

 135, B, c) upon its sum- 

 mit, while the lower part 

 remains to form a kind 

 of collar round the base 

 of the stalk. 

 217. The " urns" or spore-capsules of Mosses, which are thus 

 the immediate product of the Generative act, and which must 

 really be considered as the offspring of the plants that bear them 



' The detection of the antherozoids within the canal of the archegonium, and up"" 

 the surface of the germ-cell, is a point well worthy of JMicroscopio research. 



'0 





'i^ 











© 





Aiitheiidia and Anlherozoids of Polytrichum com- 

 mune: A, group of antheridia, mingled wiih haira and 

 sterile filaments (paraphyses); of the threo antheridia, 

 ihe central one is in the act of discharj^in^ its contents: 

 that on the left i& not yet mature, while that oti the 

 right has already emptied itself, so that the cellular 

 structure of its walls becomes apparent; — b, cellular 

 contents of an antheridium, previously to the develop- 

 ment of the antherozoids; — c, the same, showing the 

 first appearance of the anlherozoids ;—d, the same, 

 mature and discharging the antherozoids. 



