THIELAVIOPSIS PABADOXA. 527 



The siiores do not become spherical, as stated by Cobb (14). 

 The " germ tube " generally takes a tongue- shaped form, its 

 base occupying about one- half the length of the spore, but in 

 some cases it is semicircular with a base occupying the whole 

 length of the spore. After this has protruded for about 

 20-40 5/,, the apex proceeds to grow on as a normal hypha, 

 which is soon cut off by a septum from the tongue. Some- 

 times two hyjih^e are produced from the thickened germ tube. 

 , The myceUum is strikingly regular, and usually stout, 6- 8 [>. 

 in diameter. I have measured mycelium 12 [). in diameter 

 on sugar agar. In poor growths it may be only 3-4 \x 

 in diameter ; I have noticed this from spores which had 

 been kept -dry for several weeks, but the slender mycehum 

 produced thicker hyplise shortly afterwards. It branches at 

 an acute angle, the branches following the same general 

 direction as the main hypha. At first it is filled with fine- 

 grained protoplasm, but it becomes strongly vacuolate later, 

 and contains scattered, refringent granules when old. The 

 distance between the septa varies from 40 to 200 \x in the 

 main hyphae, but about 80 a is a common distance. The 

 mycehum is at first hyaline, and becomes fuliginous when old. 

 In hanging drops and flask cultures, this change is not well 

 marked ; the germ tube is usuallj^ strongly coloured, but the 

 remainder of the mycelium is almost hyaline. On solid media, 

 e.g., coconut and sugar cane, the mycelium generally becomes 

 fairly dark ; but on agar plates made with a decoction of 

 coconut stem, and therefore poor in sugar, the mycelium 

 remained white in mass during the fourteen days for which 

 it was kept. 



After about twelve hours from the time of sowing the 

 spores the formation of microconidia begins. In flask 

 cultures the surface is usually covered with white mycelium 

 and microconidiophores at the end of twenty-four hours. 

 The second form of spore— the macroconidiuin — then appears, 

 and the culture gradually becomes greenish-black and finally 

 quite black. The final change generally occurs in two days, 

 sometimes in three, from sowing ; it is due in part to a shght 

 darkening of the mycelium, but chiefly to the enormous 

 numbers of dark spores produced. 



