100 CLASSIFICATION OF THE MICRO -ORGANISMS. 



The last mode of separation of the spore, which, is very 

 peculiar, occurs in this way : the spore cell rests on the 

 apex of a tube-like basidium, which, in consequence of 

 continued absorption of water, becomes more and more 

 turgescent, while it possesses at the same time a very 

 clastic membrane ; immediately beneath the transverse 

 division the cohesion of this membrane is less than 

 elsewhere, and here, therefore, as soon as the turgescence 

 has reached a certain degree, a ringlike rupture occurs ; 

 at once the elastic wall contracts, and a large part 

 of the contained fluid is forcibly driven out of the rent, 

 and carries the spore with it. 



The spores formed by acrogenous segmentation are 

 termed basidiospores, or acrospores, or simply conidia. 

 At times this mode of spore formation occurs in fruit 

 bodies, the so-called spermogonia and pycnida. These 

 fruit bodies contain a cavity, on the inner wall of which 

 is a thick layer of basidia which give off numerous spores. 



c. Endogenous spore formation. The spores arise in 

 the interior of mother cells, the walls of which persist 

 as sporangia till ripening has occurred. The sporangia 

 are for the most part acrogenous cells ; spore formation 

 occurs in them by division of the plasma without the 

 formation of walls. The sporangia have often a club- 

 shaped or tube- like form, and are then termed asci ; in 

 these eight ascospores are usually formed. The asci arc 

 often formed in small round or flask-like fruit bodies, the 

 perithecia, which enclose a cavity, and the club-shaped 

 tubes spring from the bottom of this cavitj 7 . 



The ripe spores escape either through an opening in 

 the sporangium which is formed by sudden and great 

 swelling of a small circumscribed portion of the wall ; 

 or the largest and upper portion of the wall of the 

 sporangium becomes converted into a deliquescent 

 substance ; or, in the case of the asci, the above- 

 mentioned ejaculation of the spores is not uncommonly 

 observed. 



d. The spore formation is often preceded by a sort of 

 sexual fructification. This may consist of the so- 

 called copulation, in which two hypha?, each with a club- 



