March 1S92. 



PSYCHE. 



229 



pearance in our laboratory in 1891. 

 From this time till the middle of August 

 it multiplied its victims in the infecting 

 cases. For a short time it became 

 more conspicuous than Sporotrichum 

 and then subsided. 



On July 4th we began experimenting 

 with common shallow dry goods boxes 

 for infecting cases. The inside of the 

 boxes was sprinkled and the bottoms 

 thickly covered with green wheat. A 

 few fungus-covered bugs were sprinkled 

 over the wheat and new bugs from the 

 field were put in in large numbers. 

 Within a week the white fungus-cov- 

 ered bugs were thickly spread over the 

 bottoms and in places the white bugs 

 were literally in heaps. Continued ex- 

 periments showed that damp wooden 

 boxes offered the best conditions for the 

 development of the fungus and the glass 

 cases were no longer used. . Sporo- 

 trichum, like most fungi, thrives best 

 in a moist atmosphere, but an excess 

 of water, such as occurs in a wet soil 

 or along the sides of a glass case where 

 the vapor often becomes condensed, is 

 detrimental to its development. In the 

 wooden boxes the atmosphere was abun- 

 dantly humid ; but water that was 

 sprinkled in from time to time or that 

 became condensed on the sides of the 

 boxes was at once absorbed by the 

 wood. 



During July and August Sporotrichum 

 continued to spread through successive 

 lots of fresh bugs from the fields. Em- 

 pusa was always present but was not 

 so conspicuous in its ravages as Sporo- 

 trichum. In the first weeks of Sep- 



tember the diseases began to subside 

 and by the middle of October neither 

 Sporotrichum nor Empusa appeared to 

 be spreading further. Nor is it at all 

 probable that the diseases are lost. The 

 observations on the life history of these 

 fungi which follow show that provision 

 is made for a period of rest. 



June 28th the spores of Sporotrichum 

 were transferred by means of a sterilized 

 needle from the dead body of a chinch 

 bug to fifteen culture plates. The cul- 

 ture medium was a mixture of beef 

 broth and Irish moss ; enough of the 

 mucilaginous decoction of the moss 

 being added to the beef broth to give 

 a solid medium at So° F. Within forty- 

 eight hours the spores had germinated 

 and branching mycelia could be seen 

 spreading through the medium. With- 

 in three days spores were produced in 

 abundance, but only one spot on one of 

 the fifteen plates was found to be a pure 

 culture, Aspergillus mucor and bacteria 

 being mixed with all the other growths 

 of Sporotrichum. From the one pure 

 spot spores were transferred to three 

 new plates, and the resulting growths 

 were all pure. 



The germinating spore puts forth a 

 mycelium which branches as it grows. 

 At intervals mycelial branches shoot 

 upwards and grow over the surface of 

 the culture medium. Conidiophores 

 arise from these ; the conidiophore 

 sends oft' branches and the spores or 

 conidia are abscissed from these branches 

 in clusters. The average diameter of 

 twenty spores thus produced was 2.3 

 micromillimeters. It is by means of 



