AlorpJiology. 23 



stance, wliich, like guaiac-resin, is turned blue by 

 ozone/' 



Starch is absent from the tissues of fungi, but 

 Errera has shown '^ that glycof/en is present often in 

 considerable quantity in the vegetative and reproduc- 

 tive parts of fungi. Glycogen has the same chemical 

 composition as starch (CeH^jO-,), and is considered by 

 Errera to be of the same value in the nutrition of 

 fungi as starch is in plants possessing chlorophyll, but 

 this point is not definitely ascertained. Glycogen may 

 be distinguished from protoplasm by being more 

 highly refringent and glistening, and by its behaviour 

 when treated with iodine. If sections of tissue are 

 slightly warmed in a dilute solution of iodine (water 

 45 grm., potassic iodide 0*3 grm., iodine 01 grm.), 

 those parts containing glycogen became reddish- 

 brown or violet-brown ; the colour becomes paler 

 when heated to between 50*^ — 60^ C, and returns on 

 cooling. Glycogen can be well seen in the asci of 

 many species of Feziza after the protoplasm has been 

 used up in the formation of the spores. 



The various rejproductive bodies in fungi, collectively 

 known as spores, are either sexual or asexual in origin. 



Sexual spores originate in two distinct ways. The 

 simplest method is where two distinct branches of 

 equal size and without any apparent sexual differentia- 

 tion approach each other, the tips of the two branches 

 become swollen and filled with protoplasm, the walls 

 are absorbed at the point of contact, the two proto- 

 plasms mingle, and a new cell or spore is formed. A 

 spore produced in this way is called a zygospore, 

 '' Mem. Acad E. Sci. Belg., xxxvii. (1885.) 



