DISTRIBUTION OF SPORES AND SEEDS. 353 



movements, brought about by variations in light and tem- 

 perature, which act as stimuU. (See ^y 286.) 



II, Adaptation to distribution of spores. 



The fact that spores are found in every group of plants 

 from the lowest to the highest makes it probable that a great 



li A B 



Fig. 396. Fig. 397. 



Fig. 396. — A, riower of California poppy {Kschscholtzia), opened in siinstiine ; y>, the 



same, closed in wet weatlier. Natural size. -After Kemer. 

 Fig. 397. — W, aerial liypha of I'ilobchis ci-ystatlinus, with sporangium. The hypha is 

 swollen beneath the sporangium and \'ery turgid. B, the same with sporangium torn 

 off at base and being shot away by the violent escape of the mucilaginous contents of 

 the hypha. Magnihed about 10 diam. — After Kerner. 



variety of ways will have been adopted by plants to secure 

 their distribution. The more important ways may be grouped 

 as follows : 



478. I. By turgor and tension, — Among the fungi, spores 

 are often projected from the spore case by the pressure upon 



