76 



REPRODUCTION 



3. Summary of Reproduction in the Moss. In this life 

 cycle we have found that the moss has three methods of 

 forming more plants, i. e., of reproducing: (1) The 

 formation of spores in the capsule; (2) the budding of the 

 protonema by which erect moss plants are formed; and 

 (3) the formation of the gametes, by the union of which 

 the sporophyte arises. (Any generation of plants which 

 produces spores is a sporophyte, but that particular kind 

 of sporophyte we find in mosses is called a sporogonium. 

 The visible parts of all flowering plants are parts of the 

 sporophyte generation.) 



4. The Life Cycle of the Fern. In middle and late 

 summer we find on the under surface of the leaves of 

 oidinary ferns numerous spots. These contain many 

 spores which escape in due time. As in the moss, we will 

 begin with the spore. 



a. Germination of Spore and For- 

 mation of the Gametophyte. The 

 spore germinates by sending out 

 a tube as in the moss, but instead 

 of forming a long-branched fila- 

 ment, it divides in all planes and 

 makes a small, flat, heart-shaped 

 green body known as a prothal- 

 lium. This is not likely to be 

 seen by the student unless his at- 

 tention is called to it. It will 

 grow only in moist places. It 

 lies flat, has delicate root-like 

 structures (rhj^oids) on the un- 

 der side, and a notch at the 



prothallium is the gametophyte 



Fissure 21. Prothallia of 

 fern. The figure at the left 

 shows a young sporophyte 

 into which the fertilized egg 

 has developed. Frum Conl- 

 ter's Plant Life and Plant 

 Uses. 



growing end. 

 generation. 



This 



b. The Formation of Gametes and Fertilization. The 



green upper side of the gametophyte receives the 



