238 



BOTANY. 



The steps in the process in Mucor stolonifer are briefly as 

 follows : two hyphae come near each other, and send out 

 small branches, which come in contact with each other (a, 

 Fig. 160) ; these elongate and become club-shaped, and at 

 the same time they become more closely united to each other 

 at their larger extremities (b, Fig. 160); a little later a trans- 

 verse partition forms in each at a little distance from their 

 place of union (c, Fig. 160) ; the wall separating the new 

 terminal cells is now absorbed, and their protoplasmic con- 

 tents unite into one common mass (d, Fig. 160) ; the last 

 stage of the process is the secretion of a thick wall around 

 the new mass, thus forming a zygospore (e, Fig. 160, and z, 

 Fig. 161). 



It is interesting and instructive to note here the close simi- 

 larity between the zygospore of Mucor stolonifer and that of 

 Mesocarpus, briefly described above (par. 314). In both the 



zygospore is formed in the lateral 

 branches of the ordinary filaments. 

 320. In Piptocephalis the for- 

 mation of the zygospore is essen- 

 tially like that in Mucor, with 

 some minor differences. The 

 uniting hypha-branches are large 

 and curved, and are smaller at 

 their points of union ; the zygo- 

 Pig. i6i.-zy g ospore, n, of MU- spore is formed at first in the 



cor; m, mycelium. -After Prantl. gmall neck f orme fl ty the Union of 



the tips of the branches, but it soon grows so much as to 

 appear to be external (Z, Fig. 162). In this, as in all other 

 cases, however, the zygospore is strictly an endogenous for- 

 mation. 



" The zygospore does not germinate until it has under- 

 gone desiccation, and has experienced a certain period of 

 rest,"* when, if placed in a moist atmosphere, it sends out 

 hyphse which bear sporangia. The zygospores appear never 



* "Researches on the Mucorini," by Ph. Van Tieghem and G. Le 

 Monnier (translated in Quarterly Journal cf Microscopical Science, 

 1874, p. 49), upon which most of what is here said about the Moulds is 

 based. 



