320 Illinois State Laboratory of Natural History. 



in beef broth and then producing in cabbage worms (Pieris 

 rapw) a similar disease by moistening their food with the cul- 

 ture fluids containing the bacteria. While this disease, arti- 

 ficially induced, in some cases came so near that of the native 

 cabbage Avorm as to suggest that the bacterial treatment served 

 only to excite the natural disease of the larvae, in other cases it 

 was clearly different from the above and presented characters 

 so clearly like those of the silk worm jaundice that there could 

 be little doubt of an actual transference of the original disease, 

 especially when the blood of the sick cabbage worms was found 

 loaded with the mulberry cells and granules of pupal histolysis. 



I have next reported at length on a breeding-cage disease 

 attacking the yellow-]^ecked apple catekpillar (Datana 

 ministra) and the walnut caterpillar {Datana angusi), so 

 similar to the well-know flacherie of the silkworm that I have 

 not hesitated to call it by that name. Its principal symptoms 

 are those indicating a gradual weakening of the larvae, usually 

 accompanied by brownish fluid discharges from the vent and a 

 consequent shrinking and softening of the body. The ali- 

 mentary canal contains always great numbers of microbes, com- 

 monly of considerable variety, — including bacilli, bacteria, and 

 micrococci, the most abundant and characteristic being oval and 

 spherical micrococci not distinguishable from those mentioned 

 above. The method of the appearance and spread of the dis- 

 ease in our breeding room indicated a contagious character ; 

 and this conclusion was verified by culture of some of the bac- 

 terial forms encountered and their successful use as an experi- 

 mental virus. 



The cultures (in beef broth and on thin gelatine films) 

 related to both micrococci and bacilli, and both were preserved 

 over winter in plugged test tubes and in small sealed tubes, 

 cultivated the following season, and applied to the food of 

 another species of larva, — the zebra caterpillar {Mamestra 

 picta). The first result of this treatment was the destruction 

 of several of the larvae, in from two to six days, with a disease 

 marked by the appearance in their intestines of great numbers 

 of bacilli (in the specimens first to succumb) and micrococci 

 (later). The affection seemed then to change its character to 

 one resembling jaundice of the silkworm, the characteristic 



