308 Illinois State Lahoratoyy of Natiiml History. 



Now killing the larva, I found the fluids full of mulberry 

 cells and granules, together, with a great number of spherical 

 micrococci, — so determined by staining coagulated films. 



On the evening of July 1 a number of larvae in this cage 

 were curiously affected, the prolegs, except the anal pair, 

 being enlarged and swollen, with a slight reddish discoloration. 

 These larvae were evidently greatly annoyed by their condition, 

 and dragged themselves clumsily about as if half paralyzed. 

 One was seen to turn violently upon itself, and bite the 

 swollen prolegs, as if in pain, so that the blood flowed from 

 them freely. On the following morning one of these cater- 

 pillars was crawling about with the abdomen twisted and the 

 prolegs turned almost upwards. Carefully snipping one of 

 these swollen legs, I found in the blood an extraordinary 

 number of lymphoid corpuscles, and a very considerable number 

 of mulberry cells, but little, if any, larger than corpuscles of the 

 blood, varying from circular to oval in optical section. 

 Frequently a nucleus was visible in the midst of the mul- 

 berry granules, but no cell walls were distinguishable. The 

 unstable character of the segmentation of these cells was 

 unexpectedly demonstrated by the effect of a little carbolized 

 water run under the cover. As a consequence, the segmentation 

 entirely disappeared, the mulberry cells being all re-converted 

 into simple nucleated corpuscles with granular contents. In 

 fact, I happened to witness this retrogression of a mulberry 

 cell, — a mass of distinct granules with a nucleus dimly seen 

 among them, converted, with a curious internal commotion, 

 into a common lymphoid corpuscle, of rather large size, with 

 clearly distinguishable nucleus. In this condition the cells 

 were indistinguishable from dead blood corpuscles. No bacteria 

 were visible in these fluids. 



On the 3d July one of these larvae died. The body con- 

 tained but little fluid, but this was loaded with cells, some 

 unsegraented nucleated sphericals of various sizes, without 

 trace of cell wall, staining deeply with aniline; and others 

 well-developed mulberry cells, but so similar to the forego- 

 ing as to have been apparently derived from them. On the 

 mounted slides of this material are also great numbers of sepa- 

 rate mulberry granules and the usual spherical micrococci, the 



