310 Illinois State Lahnratory of Natiiral TJistory. 



ular protoplasm, if treated with alcohol or carbolized water. 

 In many of the mulberry cells the nucleus persisted, surrounded 

 and obscured by completely formed granules, but in others this 

 seemed likewise to have participated in the metamorphosis of 

 the body of the cell. The number of granules in a single 

 cluster varied from three or five to fifteen or twenty in an 

 optical section of the mass. The few remaining larvte of this 

 lot were now transferred to alcohol and glycerine for histo- 

 logical study. 



In the meantime matters had taken a somewhat unfortu- 

 nate course in the so-called check lot, these larvae commencing 

 to die mysteriously on the 30th of June. The first victims 

 were two dwarfed specimens which had evidently moulted very 

 imperfectly, being still covered with fragments of the old integu- 

 ment. An examination of the fluids of these specimens afforded 

 no explanation of their death, as they contained neither bacteria 

 in any appreciable number nor any cellular bodies. Another 

 affected larvae proved to have been parasitized. 



Next two larvffi were found dead upon the morning of 

 July 3, the fluids of which were grayish in hue. These con- 

 tained no recognizable bacteria whatever, but were loaded with 

 segmented mulberry cells. 



Oil the 10th of July a larva died whose blood contained a 

 moderate number of micrococci in doubles and chains, concern- 

 ing which no further notes were made at the time and the slides 

 illustrating v^^hich were lost. 



A larva evidently diseased on the evening of this day was 

 noticed the next morning with several spherical masses of 

 excrement clinging to the vent, connected with each other by 

 a delicate film. This film was dissected off, stained and mounted, 

 and found to consist of an exceedingly delicate, structure- 

 less, but rather firm, membrane (doubtless the cuticle of the 

 intestine) through which were dispersed great numbers of 

 micrococci, — unquestionably a pure culture. These were mostly 

 collected in patches, some compact and well defined, others 

 more or less diffused. The compact clusters varied in outline 

 from nearly circular to elongate oval. One of the latter was 

 35 ;u long by 8 a* wide; others were respectively 18 ^ by 20 j", 

 16 ^i by 16 i-L, and 12 ^ by 20 ^l. The micrococci composing 



