320 



MOSSES AND FERNS 



CHAP. 



BuUer also showed that the starch which is usually present 

 in the vesicle of the spermatozoid, when it escapes from the 

 antheridium, disappears completely in species where the period 

 of activity is prolonged. Thus in Gymno gramme Mertensii, 

 the swarm-period lasted about two hours, and during this time 

 the starch disappeared completely. 



Fertilisation 



Shaw (2) has made a careful study of the fertilisation in 

 Struthioptcris and in Onoclea. He states that before the arche- 



FlG. 177. — A, Osmitnda cinnamomea, section of a recently fertilised archegonium, 

 X450. A spermatozoid has penetrated the nucleus of the egg, and several are 

 in the space above the egg. B, Onoclea sensibilis. Egg fourteen hours after the 

 penetration of the spermatozoid, which is still recognizable within the egg nucleus, ' 

 X900. (B, after Shaw.) 



gonium opens, the Qgg is depressed above, and the nucleus 

 flattened. As soon as the archegonium opens, and the dis- 

 organised contents of the neck cells are expelled, the tgg 

 becomes turgid, and the depressed upper part forms the recep- 

 tive spot. (Fig. 177.) 



The mucilaginous matter ejected from the archegonium 

 retards the movements of the spermatozoids, and detaches the 

 vesicle. As the spermatozoid penetrates the neck, it becomes 

 much stretched out, and forces its way through to the central 

 cavity of the archegonium, by a slow screw-like movement. 

 Having penetrated into the ventral cavity, the coils draw 

 together again, and the movements are much more rapid. 



After a spermatozoid has entered the egg at the receptive 



