292 



Plant-Breeding 



in them. When the spores of these flowerless plants are 

 sown, a thin green tissue, or prothallus, appears and 

 spreads over the ground. In this tissue the , separate 

 sex-organs appear, and after fecundation takes place, 

 the fern, as we commonly understand it, springs forth. 

 Thereafter, this fern lives an asexual life and produces 

 spores year after year; but it is only in this primitive 

 prothallic stage that fertilization takes place, once in the 



life time of the plant. 

 If these plants are to 

 be crossed, the only 

 procedure open to the 

 gardener is to sow the 

 spores of the intended 

 parents together in 

 FIG. 99. Pollinating kit. the hope that a nat- 



ural mixing may take 



place. There are various well-authenticated fern hy- 

 brids. 



The pollination of flowers is such a simple work that 

 few implements are required for its easy performance. 

 Great care is more important than any number of tools. 

 Every one who expects to cross plants should provide him- 

 self with the three instruments shown in Fig. 91, a pin 

 scalpel, sharp-pointed scissors, and a large hand-lens. If 

 one contemplates much experimenting in this direction, 

 however, it is economy of time to have some sort of box 

 in which there are compartments for the various necessi- 

 ties. These various compartments suggest at once whatever 

 accessories are wanting, and they hold a sufficient supply 

 for several hundred operations. There should be a com- 



