JEHANGIR FARDUNJI DASTUR. 199 



place ill both its walls or in one at first, forming a round or elliptical 

 enlargement which is then cut off by two septa (Plate V, Figs. 11 and 

 13). The thickening of the wall begins at a very early stage. (2) A 

 terminal swelling appears on a young hypha, which soon becomes cut 

 off by a septum from the swelling ; the growth of the hypha is con- 

 tinued either in a prolongation of its original course or in a new direc- 

 tion by the swelling putting out a new hypha. This is not a ger- 

 mination of the swelling by a germ- tube, but it is merely a vegetative 

 growth as the swelling is immature and develops into a fully mature 

 thick- walled yellow " resting " conidium after the new hypha has 

 grown out. It is capable of germinating independently. In cul- 

 tures " resting " conidia are borne both on the aerial and submerged 

 mycelium. They are formed both in healthy and unhealthy cul- 

 tures. Extremes of temperature, which retard the formation of 

 sporangia, do not retard the formation of " resting " conidia. 

 Cultures made in May and June last (1912) produced a poor crop of 

 sporangia on account of the excessive heat in these months but 

 were rich in " resting " conidia. Very old cultures, about nine 

 months old, in which all sporangia and hyphae were dead, contained 

 living " resting " conidia. The " resting " conidia do not neces- 

 sarily require a period of rest before germinating. They germinate 

 by one or more germ-tubes quite readily (Plate V, Fig. 8). When 

 " resting/' conidia are sown in water, germination takes place within 

 twenty-four hours. Very frequently the germ-tubes are swollen 

 at the base. The germ- tubes either directly produce sporangia 

 (Plate V, Fig. 12) or " resting " conidia (Plate V, Fig. 10) or 

 vegetative hyphse. if kept moist they retain their vitality for 

 over nine months, but if they are completely dried, their germinating 

 power does not last for even a week. 



That the " resting "conidia are pathogenetic oospores is very 

 improbable for the reason that they are over twice the size of 

 normal oospores and that from the very beginning of their develop- 

 ment they are thick-walled and slightly yellow tinted, while 

 pathogenetic oospores have their origin in thin-walled and 

 hyaline oogonia which, on failing to come in contact with antheridia 



