CONJUGATING FUNGI— PHYCOMYCETES 231 



germinate at once through a lateral pore, but in the latter 

 case an intermediate stage intervenes. Each gonidium when 

 mature has more turbid contents, which are seen to accumulate 

 in several centres, and then to become divided by the growth 

 of a membrane about each segment, into distinct inner cells, 

 each with a nucleus. 

 Soon the wall of the 

 mother cell is rup- 

 tured, and the con- 

 tents escape, now 

 differentiated into 

 three or four, or more, 

 smaller but similarly 

 shaped bodies, armed 

 with a pair of vibra- 

 tile cilia, by means 

 of which they move 

 actively in any drop 

 of moisture with 

 which they may come 



in contact, trans- FlG> 1°6.-Gonidiopliore of Peronoxpora. 



formed into secondary gonidia or zoogonidia, sometimes called 

 zoospores. In this condition they move about for some time 

 over the moist surface of the leaf upon which they are 

 discharged, until at length they come to rest, lose their cilia, 

 and commence germination, by the production of a delicate 

 germ-tube which enters the stomata of the fostering plant, 

 and form a mycelium beneath the surface. From this my- 

 celium spring erect hyphae, which seek the air, and, becoming 

 branched, constitute new gonidiophores, and the cycle is 

 complete. 



The sexual reproduction takes place within the host-plant, 

 by the production of oogonia upon branches of the mycelium. 

 They originate as spherical swellings at the end, or inter- 

 calated in the hyphae, and after a time reach a considerable 

 volume, and contain a dense protoplasm with oil drops. Soon 

 these swellings are isolated by the production of a septum 

 across the hypha when terminal, or above and below when 

 intercalary. After this differentiation of the oosphere takes 



