FERNS. 



181 



These are the an- 



tered over this portion of the prothallium. 



theridia. Ifthepro- 



thallia have not been 



watered for a day or 



so, we may have an 



opportunity of see- 

 ing the spermato- 



zoids coming out of 



the antheridium, for 



when the prothallia o antheridia sh ^ 3 sperm cellSj and spermato . 



are freshly placed in >ids in the one at the right. 



water the cells of the antheridium ab- 

 sorb water. This presses on the con- 

 tents of the antheridium and bursts the 

 cap cell if the antheridium is ripe, and 

 all the spermatozoids are shot out. 

 We can see here that each one is 

 shaped like a screw, with the coils at 

 matozoids; first close. But as the spermatozoid 



motion (Adiantum concinnSin) 44 ' '" begins tO lllOVC this coil Opens SOme- 



what and by the vibration of 

 the long cilia which are on the 

 smaller end it whirls away. In 

 such preparations one may often 

 see them spinning around for a 

 long while, and it is only when 

 they gradually come to rest 

 that one can make out their 

 form. 



373. Archegonia. If we now 

 examine closely on the thicker 

 part of the under surface of the 

 prothallium, just back of the 



" sinUS," We may See longer venter'is Ae* egg 1 , next' is 7he*ventral canal 



cell, and in the canal of the neck are two 

 StOUt projections from the Surface nuclei of the canal cell. 



of the prothallium. These are shown in fig. 214, They are 



Fig. 224. 



Different views of s 

 42, 43, in a quiet c 



Fig. 225. 

 Archegonium of fern. Large cell in the 



