116 CONJUGATION. [CH. VIII 



called suspensors an unnecessary term. The zygospore 

 is endowed with a certain persistence of vitality, so that 

 after the crop of Mucor has died and disappeared, the 

 zygospore is left alive, isolated in the nutritive sub- 

 stratum. After some weeks of rest it germinates, i.e. 

 begins to grow. The thick outer coat bursts and the 

 inner cell-wall grows out into a stout mycelial tube or 

 hypha. This hypha may either at once proceed to form a 

 sporangium, or it may branch once before it does so, but 

 in any case it does not form a complex web of mycelium 

 like that produced from a sporangial spore. 



Spirogyra. Conjugation. 



Spirogyra (as described in Chapter I.) is an Alga, 

 having the form of a delicate filament, each filament being 

 made up of a simple row of cells. The process of conju- 

 gation takes place between the cells of neighbouring 

 filaments. A number of cells in each of the filaments put 

 out processes, simple tubular outgrowths from the cells, 

 which meet, coalesce and finally become converted into 

 tubes uniting cell to cell as shown in fig. 51. The contents 

 of the conjugating cells contract and the rounded masses so 

 produced are the elements which fuse together in the act 

 of conjugation. The balling of the protoplasm begins in 

 one of the conjugating cells before it is perceptible in the 

 other. The protoplasts which are thus early in contracting 

 have a certain masculine character, inasmuch as they are 

 more active than the protoplasts with which they conju- 

 gate. They travel through the connecting tube and by 

 fusion with the stationary protoplasts they form zygospores. 



