Observations on Growth of Fungus Parasitic on Locusts. 69 



us for investigation from King William's Town in May, 1896, thus 

 showing that the fungus was spread over a large area of South Africa. 



Cultivation Experiments. 



I now made an attempt to get a pure cultivation of the fungus, 

 using as a medium for growth sloped glycerine-agar of the ordinary- 

 composition. I inoculated the medium with a platinum loop rubbed 

 over with the teased connective tissue in which the mycelium was 

 found. In twenty-four hours, at a temperature of 30° C, small 

 yellowish translucent islets were visible on the surface of the medium ; 

 they had a radiate appearance and cog-wheel-like edges ; in thirty- 

 six hours they had increased in all directions, forming small circular 

 patches, one-fourth of an inch in diameter, and a slight velvety 

 growth was visible both aerially and into the substance of the 

 medium. Growth in all directions was now vigorous over the 

 surface of the medium, and the aerial growth, and that into the 

 substance of the medium also increased ; in forty-eight hours the 

 velvety aerial growth could be seen dotted over abundantly with dark 

 points which on a microscopic examination were found to be spore 

 cases. After this reproductive effort the formation of spore cases 

 apparently ceased but vegetative growth of the aerial filaments con- 

 tinued until the surface was covered with a thick filamentous grey 

 mycelial growth ; the strength of this aerial growth evidently 

 depended to a large extent on the nutritive pabulum ; for on less 

 nourishing media, such as potato, it was far less abundant and slower 

 in development. I noticed in growing it on potato that the growth 

 continued for some time short and scanty, resembling in appearance 

 that on the integument of the locust, and then the growth suddenly 

 became vigorous and abundant. This increase of vitality I took to 

 be due to self-sown spores growing on the decayed tissues of the 

 earlier fungoid growth, thus obtaining a more suitable pabulum as 

 will afterwards be seen. 



Microscopic Examination on Growth of Medium. 



On examining the edges of the growing islet of fungus it was seen 

 with a low power to be composed of the interlacing filaments of a 

 fungus ; the mycelium was composed of filaments branching alter- 

 nately ; the filaments being formed of elongated cells with no other 

 differentiation of structure ; the protoplasm in some of the filaments 

 was clear and homogeneous, in others very granular, with large 

 vacuoles scattered through the protoplasm of the cell ; experience 

 showed that this granuality and vacuolation was an accompaniment 

 of active growth. Wherever active growth, either vegetative or sexual, 



