300 Illinois State Laboratory of Natural History. 



those on the slide already described ; and even on April 24 of the 

 following year, the test tube, which had been preserved over 

 winter, yielded only the same Micrococcus, as shown by well- 

 stained and mounted slides prepared at that time. Magnified 

 1400 diameters and carefully measured, the single spherules 

 vary from 1 ^ to 1.25 A* in diameter. 



From the foregoing I infer a verification of the experiment 

 just reported, by a second successful culture of the spherical 

 Micrococcus of the Datana larva and its preservation, uncon- 

 taminated, until the following year. 



The only gelatine film cultures made with this material 

 were begun September 8. Six films of solid beef gelatine, 

 touched with a needle point dipped into the fluids of a larva 

 of Datana ministra and inverted over a deep" cell containing a 

 droplet of distilled water to prevent drying out, exhibited Sep- 

 tember 10 a rapid growth of the infection, each, originally a 

 mere point, being now about the diameter of a pin head, and 

 some having penetrated upwards the thickness of the film. 

 The growth of this mass was in the form of thick finger-like 

 processes, extending upwards through the gelatine film, the 

 marginal increase however being uniform and continuous. 

 When warmed, these gelatine-film bacteria took on the flagel- 

 late motion of Bacillus, and the stained slides made from them 

 strongly indicate that they are young individuals of Bacillus 



intrapaUens. 



INFECTION EXPERIMENTS. 



A few experiments with cultivated material were made 

 upon other Datana larvae obtained from time to time out of 

 doors, these being divided into experimental and check lots, and 

 the food of the former treated with infusions containing the 

 cultivated bacteria. These were among our first experiments, 

 and the control cages were evidently imperfectly isolated. As 

 a consequence, the experiments were brought to naught by the 

 appearance of flacherie in all the cages with which we had to 

 do. In each instance, however, the mortality was more imme- 

 diate, and at first much greater, among the lots treated with the 

 bacterial cultures than among those not purposely infected ; 

 but the results arrived at are not insisted on, and no detailed 

 account of these experiments is deemed advisable. 



