CHAPTER III 



SPORE WALLS AND SPORE DISPERSAL 



The Cell-walls of Basidiospores, Teleutospores, Uredospores, and Aecidiospores — 

 Compact and Loose Teleutospore-sori — Spore-wall Pores — The Number of 

 Uredospores and Aecidiospores of Pnccinia graminis — The Violent Discharge 

 of Aecidiospores — The Dispersal of the Spores by the Wind 



The Cell-walls of Basidiospores, Teleutospores, Uredospores, 

 and Aecidiospores. — The long curved isolated basidia of the Ure- 

 dineae are particularly dependent for their successful development 

 upon the amount of moisture in the atmosphere ; and it is not 

 surprising, therefore, that they are only produced in moist weather 

 and that, when moist weather comes, they develop and discharge 

 their spores as quickly as possible. Now the walls of the basidio- 

 spores of the Uredineae, like those of the Tremellineae and of many 

 non-gelatinous xylophilous Agaricineae, are always smooth and 

 thin and colourless. These characteristics, here as in the other 

 fungi, are correlated with the rapidity of development of the indi- 

 vidual spores. A spore, if it is to be developed and discharged in 

 a minimum amount of time, must have a very simple wall, i.e. 

 the wall must be smooth and thin and colourless, for only such 

 walls can be produced by the simplest means and by the least 

 amount of physiological action. ^ 



The walls of teleutospores are usually thick and impregnated 

 with a brown pigment. Since teleutospores, relatively to the 

 basidiospores, develop very slowly, there is plenty of time for this 

 cell- wall elaboration. Teleutospores are resting bodies and often 

 persist upon their hosts for weeks or months before germinating. 

 Their thick walls probably have a protective significance. The 

 brown pigment in the cell-walls may possibly be a waste product 



1 CJ. these Researches, vol. ii. 1922, pp. 49, 161. 



540 



