70 Transactions of the South African Philosophical Society. 



went on there the growing cell showed granularity of protoplasm ; 

 a faint yellowish colouring of the protoplasm was often seen in these 

 conditions. Such was the appearance of the filaments twenty-four 

 hours after inoculation ; but after forty-eight hours very considerable 

 differentiation of structure was apparent. Then a form of asexual 

 reproduction made its appearance, rapid segmentation of the filaments 

 taking place, followed by the throwing off of buds. This gemmation 

 takes place on the filaments growing along the surface of the medium, 

 on the perforating and on the aerial filaments. The formation of 

 conidia is preceded by the rapid segmentation of the terminal 

 mycelial filaments which at the same time show granularity, pig- 

 mentation, and vacuolation of the protoplasm. Once the process 

 of segmentation begins, it goes on with the most extraordinary 

 energy ; buds are thrown off in all directions and on separating 

 reproduce the process. The conidia thrown off are ovoid or circular 

 in contour, and of varying sizes, some being small, not measuring 

 much more in diameter than a white blood corpuscle, while others 

 are from three to six times larger. The margins show a double 

 contour, this appearance being no doubt due to a thin cell wall ; the 

 enclosed protoplasm is often vacuolated and irregularly granular ; 

 what appears to be a nucleus is often seen, the protoplasm of which 

 is darker and more homogeneous. These separated conidia repeat 

 the vegetative cycle with great rapidity either by budding or by 

 elongating ; a process being pushed out by the cell wall which takes 

 part in the prolongation. It appeared to me that the initial division 

 nearly always began with the nucleus when that was visible, the 

 cell then elongating, and a septum forming which separated the new 

 from the germinating cell. Actual gemmation, however, often seemed 

 to take place, portions of protruded protoplasm being cut off by con- 

 striction of the cell wall. The new cells and buds could be separated 

 with great ease from the germinating cell and then they immediately 

 reproduce the same process ; in this way from a single cell long 

 filaments were formed which branched alternatively, the branches 

 often forming conidia and throwing them off. Such is the vital 

 process of the formation of mycelium as is found on the surface of 

 the nutritive medium and the filaments which, penetrating root-like 

 into the medium, show the same characters and formation. These 

 penetrating filaments, however, always ceased to invade the medium 

 deeper than -J- to ^ of an inch. This stoppage of growth probably 

 points to the necessity of considerable oxygenation as requisite to 

 the vital process. 



The aerial growth, however, which begins in the same way and 

 goes through the processes above described, soon takes on a true 



