4 FUNGUS-FLORA. 



the ascus, most capable of expansion, is frequently much 

 thicker than the lower portion, and in many species assumes 

 a clear blue colour when treated with a solution of iodine, a 

 plug occupying the apex becoming darkest in colour. This 

 iodine reaction is frequently included in the specific diagnosis 

 by Eehm, in his work on the Discomycetes in Eabenhorst's 

 "Kryptogamen- Flora." In some species the apex of the ascus 

 is ruptured in an irregular manner, in others there is a long 

 slit, while in others again, as in many of the Ascoboleae, the 

 apex opens by a distinct circular lid that remains upraised 

 and attached by one side after the spores have escaped. 

 Boudier, a French Mycologist, has proposed a classification 

 of the Discomycetes, based on the mode of opening of the 

 apex of the ascus ; the arrangement, however, has not been 

 adopted, as the character can only be distinctly observed in 

 the fresh specimen. 



In some species, clouds of spores are given off at maturity ; 

 this process is known as puffing, and is due to the simultaneous 

 dehiscence of numerous asci. Shaking or breathing on the 

 fungus causes this, which is considered by De Bary to be due 

 to the sudden loss of water, the act being accelerated by 

 whatever aids transpiration. No puffing is caused by shaking 

 or otherwise if the fungus is shut up in a damp atmosphere. 

 This, however, does not explain the matter entirely, as fungi 

 will often puff after lying in a room for some hours, if moved. 

 The phenomenon appears to depend on a difference of tension 

 being brought about in the walls of the asci. 



In Ascobolus and allied genera the asci expand so much 

 that they project far above the surface of the hymenium at 

 maturity ; dehiscence takes place by the spores being ejected 

 through a definite aperture formed by the opening of a 

 circular lid at the apex, the ascus remaining fixed at the base, 

 and not being ejected bodily, as is sometimes believed. After 

 dehiscence the ascus shrivels and contracts. 



Spores. The ascus when quite young is filled with 

 finely granular, vacuolated protoplasm, in which a single 

 nucleus is imbedded; as the ascus increases in size two 

 nuclei are present, at a later stage four, and eventually eight 

 nuclei can be seen ; these eight nuclei are the starting-points 

 for the formation of the eight spores, which are formed 



