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MORPHOLOG V. 



Fig. 218. 

 Spores of asplenium ; exospore re- 

 moved from the one at the right. 



point. A spore of the Christmas fern is shown in fig. 216. The 

 outer wall here is more or less winged. At fig. 217 is a spore 



of the same species from which the 

 outer wall has been crushed, showing 

 that there is an inner wall also. If 

 possible we should study the germi- 

 nation of the spores of some fern. 



368. Germination of the spores. 

 — After the spores have been sown for 

 about one week to ten days we should 

 mount a few in water for examination 

 with the microscope in order to study 

 the early stages. If germination has begun, we find that here 

 and there are short slender green threads, in many cases attached 



to brownish bits, the old 

 walls of the spores. 

 Often one will sow the 

 sporangia along with the 

 spores, and in such cases 

 there may be found a 

 number of spores still 

 within the old sporan- 

 givim wall that are ger- 

 minating, when they will 

 appear as in fig. 219. 



369. Protonema. — 

 These short green threads 

 are called protonemal threads, or protonema, 

 which means a first thread, and it here 

 signifies that this short thread only pre- 

 cedes a larger growth of the same object. 

 In figs. 219, 220 are shown several stages of 

 germination of different spores. Soon after 

 Germinat'ing^spores of the short germ tubc emerges from the 

 s^p'orangi^m'"'' '"" '" "" crack in the spore wall, it divides by the 



