172 



BOTANY. 



282. Archegonia. If we now examine closely, on the thicker 

 part of the under surface of the prothallium, just back of the 



45 



Fig. 147. 



Mature and open archegonium of fern (Adiantum cuneatum) with spermatozoids making 

 their way down through the slime to the egg. 



"sinus," we may see longer 

 stout projections from the sur- 

 face of the prothallium. These 

 are shown in fig. 139. They are 

 the archegonia. One of them 

 in longisection is shown in fig. 

 146. It is flask- 

 shaped, and 

 the broader 

 portion is sunk 

 in the tissue of 

 the prothal- 

 lium. The egg 



ap 



is in the larger Fig. 148. 



rt T h P Fertilization in a fern 



P ai u e (marattia). s/>, spermato- 



crirmat^-7rn'rlc zoid fusing with the nu- 



spermatozoids cleus of t ^ e egK (After 



Fig. 149. 



Young plant of Pteris serrulata still 

 attached to prothallium. 



when they are Campbell.) 



swimming around over the under surface of the prothallium 



