234 INTRODUCTION TO THE STUDY OF FUNGI 



the common ovate form, with a pair of active cilia at the 

 smaller end. At maturity they escape by an orifice at the 

 apex, and swim freely and actively in the surrounding water. 

 In addition to this asexual reproduction, there is a more com- 

 plex system of sexual reproduction, by means of antheridia and 

 oogonia, the resultant oospores, or resting spores, serving to 

 carry the germs through the winter and provide for their 

 appearance in the spring. In typical species the sexual appa- 

 ratus is of this kind, the oogonia are globose cells, generally 

 terminal on short branches of the mycelium (Fig. 109). The 

 external membrane is absorbed at various points, leaving it 

 pierced with rounded holes. The pro- 

 toplasm becomes divided into a greater 

 or less number of distinct portions, 

 which become rounded into little spheres 

 and separate from the walls of the cell 

 to congregate in the centre, where they 

 float in a watery fluid. During the 

 formation of the oogonium, there arise 

 from its pedicel, or the neighbouring 

 filaments, thin curved branches, which 

 are sometimes twisted round the pedicel, 



Pig. 109. — Oogonium with . _,, . 



twooospheresof^cMya. but tend towards the oogonium. Ineir 

 After De Bary. f ree extremity is closely applied to the 



wall, and becomes slightly inflated above, and cut off below by a 

 septum. It is then an oblong cell, or antheridium, filled with 

 protoplasm. Each oogonium possesses one or several of these 

 antheridia. Towards the time when the oospheres are formed, 

 each antheridium projects into the interior of the oogonium one 

 or more tubular processes, which are applied by their extremities 

 to the nearest oosphere. They have not been seen to open, 

 nor has anything like a discharge of protoplasm been/observed. 

 Afterwards the oospheres become covered with cellulose, and 

 are converted into so many oospores. When they have arrived 

 at maturity these oospores possess a tolerably thick integument, 

 which is double, and, after a considerable period of rest, they 

 develop germ tubes or sporangia direct. 



The Entomophthoraceae are minute parasites which inhabit 

 the bodies of small flies and other insects, and are " distin- 



