184 Scientific Proceedings, Royal Dublin Society. 



When coaidia are transferred from flasks of bog-soil water to hanging 

 drops of tap-water, or even when they develop in droplets of condensed 

 water in cover-glass film-cultures, it frequently occurs that they burst at 

 some point in their periphery, often, but not alwaj's, at the apex, and 

 through the opening the disorganized contents more or less slowly ooze out. 

 This condition is illustrated in Plate XIII, fig. 4. No satisfactory expla- 

 nation for this behaviour can be given at present. It, however, seems to 

 occur chiefly when the conidia are unripe, and may, perhaps be due to osmotic 

 phenomena induced by a change in concentration in the surrounding 

 medium. 



The germ-tubes produced direct from the conidia do not differ essen- 

 . tially from ordinary hyphae. They may arise at the apex or, perhaps more 

 frequently, a little to one side of it, but they may also arise at almost any 

 other point on the periphery of the conidium. Two or three such germ- 

 tubes may sometimes be seen arising from different points on one conidium ; 

 and very frequently a germ-tube gives rise to two or tliree brandies almost 

 immediately after it leaves the conidium. A couidium which has developed 

 a germ-tube from near its apex is illustrated in Plate XIII, fig. 6. 



The conditions which decide as to whether conidia shall produce germ- 

 tubes or zoospores are not yet known. As was explained, however, in the 

 former paper, considerable difficulty was at first experienced in securing the 

 formation of zoospores. Further observations seem to show that attempts 

 to stimulate their production by artificial means are useless, so long as the 

 conidia are not fully ripe, and that when they are ripe such stimulation is 

 not necessary. 



The minimum time in which zoospores have been observed to be produced 

 on germination is a period of seven days elapsing since the medium or tissue 

 containing the fungus mycelium was placed in water to induce the formation 

 of conidia ; but in some cases this period extended over twelve days. When 

 the necessary time has elapsed, zoospore formation can be observed with 

 ease by removing mycelium bearing conidia from the bog-soil water in 

 which they have developed to hanging-drops of tap-water at room- 

 temperature. Zoospore production commences as a rule withiu about an 

 hour after the preparation of tliese drops. 



Previous to the liberation of the zoospores, the contents of the conidium 

 (zoosporangium) change from a finely to a coarsely granular condition ; the 

 large oil-drop, if present, disappears as such, becoming broken up into a large 

 number of smaller ones. Soon the segregation of the protoplasm into zoospore 

 units begins to take place within the sporangium ; and these units can be 

 seen clearly, although their total number cannot usually be determined with 



