PUFFING 239 



brought into contact with the preparation, after a time the asci one 

 by one contracted suddenly without discharge. Evidently their 

 turgidity became lost owing to the death of the protoplasm lining 

 the ascus wall. Sodium carbonate also did not cause ascus discharge, 

 although the asci died from its effects. Up to the present, therefore, 

 it seems that non-poisonous substances and alkalies do not cause 

 puffing, whereas poisonous substances, excluding alkalies, do. Why 

 alkalies should behave differently to other poisonous substances 

 seems for the present inexplicable. 



In one experiment an ascus was caused to contract considerably 

 with potassium nitrate. It did not explode. It was then restored 

 to its former size by placing it in water. When brought into contact 

 with iodine dissolved in water, it immediately exploded without 

 undergoing any preliminary measurable decrease in volume. This 

 observation will serve to emphasise the difference in action between 

 a neutral salt which merely withdraws water from an ascus, and a 

 non-alkaline poisonous substance which affects the protoplasm. 



Asci which have contracted in volume owing to loss of water on 

 treatment with a strong solution of a neutral salt, may be caused to 

 explode when brought into contact with iodine. The explosions 

 under these conditions are naturally comparatively weak, and the 

 spores shot out from the asci travel but a very short distance from 

 the ascus mouth. 



The experiments just recorded seem to me to suggest that the 

 bursting of ripe and expanded asci is not brought about by an 

 increase in the pressure of the cell-sap upon the ascus lid, but rather 

 by an alteration in the strength of attachment of the ascus lid to the 

 rest of the ascus wall. We may regard the protoplasm at the end of 

 the ascus as specially entrusted with the work of loosening the 

 attachment of the ascus lid, as its final duty. By suitable stimula- 

 tion of this guardian protoplasm, the attachment may be indirectly 

 loosened and thus an ascus explosion brought about. Possibly the 

 necessary stimulus can be given mechanically, as when a sporocarp 

 is caused to puff by mere moving or shaking; possibly it may be 

 given by a sudden withdrawal of water from the end of the ascus, as 

 when a sporocarp is caused to puff by suddenly allowing it to come 



