Germination of resting -spores 



a gradually widening aperture and then is itself exuded as an envelope 

 for the escaped cell. The latter now begins to divide and forms a new 

 plant. (Fig. 18, A, B, and C.) 



(2) The first division of the protoplast occurs within the walls of the 

 spore, and this may be followed by other divisions, so that from two to four 

 cells may be formed before the spore-wall is burst open. Succeeding 

 divisions then cause the free end of the young filament to extend further 

 and further from the spore, although the other extremity may not free 

 itself from the old spore-wall for some time. (Fig. 18^1, the lowest spore 

 in the figure.) 



Fig. 18. A and B, germination of the spores of Anab&na azoll& Strasb. ; A, x 680 ; B, x 850 

 (after Fritsch). In A, two spores show germination of the first type, and the lowest spore 

 germination of the second type. In B, variations of the first type of germination are shown. 

 C and 7), germination of the spores of Anabfena cycadearum Eeinke; C illustrates the first 

 type of germination and D the third type; x 2200 (after Spratt). E, germination of a spore 

 of Oscillatoria sp. (possibly 0. limosa Ag.) ; x about 700 (after Phillips). 



(3) Both walls of the spore may swell up and become mucilaginous, 

 forming a gelatinous envelope of considerable dimensions. The protoplast 

 sooner or later begins its division within this wide coat of mucus. (Fig. 18 D.) 



The first type of germination occurs more frequently than the other two. 

 In Anabfena and Nodularia the spores may germinate while still attached 

 end to end, but this is not usual in other genera. 



Reproduction has been found to occur by Sauvageau ('97) in Nostoc punctiforme by the 

 formation of ' cocci,' which are small cells about the same size as the vegetative cells. 

 They occur in large numbers, probably consisting of free vegetative cells, and were 



