432 



STRUCTURE AND LIFfe KCSTOEIES 



tance, in the ascending scale, of gametophyte and sporo- 

 phyte, and the evidences which point to a possible mode of 

 origin of the vegetative body of the sporophyte. A funda- 

 mental question, still being debated by botanists, is 

 whether, in racial history, the vegetative (sterile) tissue 

 appeared first, and the sporogenous (fertile) tissue later. 



Fig. 321. — Diagram of the life-cycle of a pine. (After Schaffner.) 



or whether the fertile tissue appeared first. The question 

 may be put^as follows: Is the cone (strobilus) the older 

 structure in the development of the race, and are the vege- 

 tative parts to be regarded as developed from it__by pro- 

 gressive sterilization? It is better that this question be 

 merely stated here, as one of the larger, fundamental 

 problems of botany, and that the pleasure of discussing 

 it be reserved for the teacher and students together, in 

 connection with a later chapter. (Cf., also, p. 379.) 



