THE president's ADDRESS. 



257 



The spores, which are produced in asci, or mother-cells, usually 

 eight spores in each ascus, are also often coloured. In the genus 

 Ascobolus the spores are at first clear green, changing to a 

 brilliant amethyst or violet, and finally dark brown and opaque. 



The spores of many fungi that grow only on dung, and 

 require to pass through the alimentary canal of an animal 

 to induce germination, have a coloured cell-wall, and are very 

 resistent to the action of acids and alkalies. This structure 

 probably serves to protect the spores in their passage through 

 the alimentary canal. 



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Fig. III. 









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Fig. IV 



The last in the sequence to appear are members of the 

 Pyrenomycetes. These agree with the Discomycetes in having 

 the spores produced in asci, but differ in having the asci 

 completely enclosed in a special structure called the perithecium, 

 which is furnished at the apex with, a minute aperture through 

 which the spores are ejected when mature. The opening or 

 mouth is often situated in the centre of a little nipple- like 

 swelling at the apex of the perithecium, or in some instances 

 occupies the apex of a more or less elongated beak, as in 

 Fig. VI. 



The perithecia are usually blackish or dingy olive, smooth, 



