i8 



GENERAL MORPHOLOGY. 



Whichever is right, one thing is certain, namely, that a structure 

 very similar to a zygospore can be produced without cell fusion 

 of the kind described. In such event the resulting body is 

 called, for the sake of distinction, an azygospore or partheno- 

 spore. This kind of spore can be formed in several ways, one 

 of them differing from the foregoing merely in that the partition 

 between the gametes is not absorbed, and consequently no fusion 

 of the cell contents takes place, each gamete ripening apart to 

 form a spore ; i.e. two azygospores are produced. An example of 

 this type is given in Fig. 102 {a). In other instances, however, 

 the process is fui-ther simplified, inasmuch as no contact occurs 

 between the two club-ended hyphae, but each (or one) of the 

 gametes {h, Fig. 102) develops of itself into an azygospore. In 

 still another instance, even the endeavour of two hyphae to 

 approach one another is absent, the azygospores forming quite 



a h 



Fig. 102. — Formation of Azygospores in Mucor erectus. 

 {After Bainier.) 



alone and independently at the extremities of branches ; an 

 example of this method of sporulation is afforded by 3hicor 

 tenuis (§235). 



Ehrenberg, in 1829, was the first to observe zygospores, the 

 organism examined being Sporodinia grandis (§ 235), wherein 

 these spores attain a diameter of about 0.25 mm. It was not, 

 however, until 1864 that the method of production and germina- 

 tion was made clear by the researches of A. de Bary. Seven 

 years later, Brefeld (I.) established the new order (class) of the 

 Zygomycetes, comprising all the fungi capable of producing 

 zygospores. These are all, without exception, Phy corny cetes. In 

 addition to this faculty, which distinguishes and separates them 

 from all other fungi, the different genera of the Zygomycetes 

 have, in common, various other properties which reveal their 

 mutual relationship and therefore justify their classification into 

 a special group, as expressed in the scheme drawn up a few 

 pages back. This class of the Zygomycetes is the only one among 

 the Phycomycetes that possesses any importance for the fermenta- 

 tion industries ; it will be found treated in Section xi. 



The conditions under which the formation of zygospores 

 occurs must not be left out of consideration, since they show 

 that, here as in other cases, the development of fungi, like that 



