ZTGOPHYTA. 



127 



the nutritive medium, come near each otner, and send out 

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

 Fig. 59); these elongate and become club-shaped, and at 

 the same time they become more closely united to each 

 other at their larger extremities (b) ; a little later a trans- 

 verse partition forms in each at a little distance from their 

 place of union (c) ; the wall separating the new terminal 



«/ 



Fio. 59. — Conjugation of a Black Mould, a. two hyphae near each other, and 

 Bending out short lateral tuhes or branches, which come in contact; 6, the 

 branches grown larger; c, the formation of a partition near the end of each 

 branch ; d, absorption of the wall between the two branches, and the consequent 

 union of the protoplasm of the end cells; e, resting spore fully formed, e mag- 

 nified 90 times, the others nearly the same. 



cells is now absorbed, and their protoplasmic contents unite 

 into one common mass (d); the last stage of the process is 

 the secretion of a thick wall around the new mass, thus 

 forming a zygospore (e).. 



268. The resting spore does not germinate until it has 

 undergone desiccation, and has experienced a certain period 

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

 hyphse which bear spore-cases. Resting spores appear never 



