138 



FERN. 



[CH. X 



the life-history of the plant and is of no further use except 

 as a supply of food material for the embryo; and this 

 supply is drawn by the foot acting like a sucker or root. 



FIG. 62. 



DEVELOPMENT OF THE SPOROPHYTE OP THE FERN FROM THE 

 EGG-CELL, diagrammatically represented. 



In the upper figure the embryo is made of a number of cells, the four 

 thick lines represent the cell-walls by which the egg-cell was 

 partitioned in the early stages. 



Of these four cells, s and Z develope into stem and leaf; 



r and /, into root and foot, as may be seen in the lower figure. 



a, a, unfertilised archegonia. 



rh, root-hairs on the lower surface of the prothallus. 



The embryo is contained in a swollen and distorted archegonium. 

 (After Mangin.) 



We thus get this remarkable state of things ; that the de- 

 veloping sporophyte remains attached, by an absorbing 

 organ, to the oophyte which gave it birth ; the sporophyte 

 lives in fact like a parasite on its parent. This arrange- 

 ment is only temporary, after a time the prothallus dies 

 and the sporophyte grows into a massive leafy plant 

 capable of self-support. 



