GENERAL MORPHOLOGY. 107 



shaped protrusion, grow towards one another, unite after 

 absorption of the opposing walls, and form a zygospore. 

 For the most part, however, well-marked male and female 

 sexual organs are formed. The female is attached to a 

 mycelium thread in the form of a glohular swollen cell, 

 and is termed oogonium ; the male, antheridium, is a 

 long or club-like swollen cell which attaches itself to the 

 oogonium and becomes separated from its hypha ; at 

 times the antheridium sends a so-called fertilising tube 

 into the interior of the oogonium. After fertilisation, 

 the oosporcs, which are globular cells provided with a 

 cellulose membrane, are formed in the oogonium. Such 

 anastomoses between hyphre do not, however, in all cases 

 indicate a sexual copulation. 



The ripe spores are for the most part simple, often, structure of 

 however, composite, cells of very varying forms ; usually * 

 they are spherical or oval ; at times, however, they have 

 the form of long thin rods. The wall consists of an 

 external, and often coloured sheath, the episporium, and 

 an inner, more delicate, colourless layer, the cndosporium. 

 The contents consist of protoplasm, and oil globules 

 are frequently present. The general distinctive cha- 

 racteristic of the spores is that they either become 

 converted into the mother cells of new spores, sporangia, 

 or send out one or more germinating tubes from which 

 the mycelium threads may again develop. 



The swarming spores and the resting spores behave 

 somewhat differently. The former are round, naked pro- 

 toplasmic bodies without a firm cellulose envelope, pro- 

 vided with two cilia, and thus capable of movement; they 

 arise endogenously from the spores by division of the spore 

 contents, and become free by swelling of the sheath of the 

 sporangium. They are only formed and liberated under 

 water. After the mobile, naked stage has lasted for a 

 short time, the swarming spores come to rest, surround 

 themselves with a cell wall, and then, like other spores, 

 send out a germinating tube. By resting spores we 

 understand those spores which are not able to germinate 

 immediately after their formation, but require first a 

 period of rest, e.g., a whole winter. Zygospores and 



