214 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



Between these are various intergrades. The miliar class or type 

 pertains usually to the acute form of the disease, while the nodular 

 class or type is more distinctive of the chronic form; but numerous 

 cases graduate from acute to chronic so that it is difficult to classify 

 them. After a variable but always long duration, often of months, 

 the eruption begins to decrease, loses its color, hardens, becomes 

 encrusted, and finally sloughs without leaving any scar in the case of 

 the true miliar and nodular types; but the enlarged types, mular and 

 pseudomular, leave a whitish or pigmented mark on sloughing. The 

 mular may attain such dimensions as to break of its own weight, 

 admit germs, suppurate or ulcerate. 



The only bodies yet found in the blood that can possibly be connected 

 with verruga are Barton's x-bodies, discovered by Dr. A. L. Barton, 

 of Lima. Dr. S. T. Darling, Chief of the Ancon Hospital Laboratory 

 of the Canal Zone, has given a good account of them in the Jour- 

 nal oj the American Medical Association for December 23, 1911, from 

 which the following points may be taken: They are endoglobular and 

 seen first as slender rod-like forms with rounded free ends, but cannot 

 be detected in the fresh blood; thus their refractive index must coincide 

 with that of the erythrocyte. The rods are occasionally single, oftener 

 two or more up to six or eight and frequently grouped in parallel 

 series. Some show filaments or irregularly disposed branches or 

 pseudobranches. They stain dark blue or purple and never faintly 

 blue with chromatin differentiation. After a few days they lose the 

 slender form, swell irregularly^, distort and become fragmented. If 

 the disease progresses favorably the rc-bodies disappear and the erup- 

 tion comes out. Should the a:-bodies reappear in their slender form 

 and continue in large number in the peripheral blood, the patient dies. 

 In all cases, according to Barton, the recovery of the patient coincides 

 with disappearance of these x-bodies from the peripheral blood. 



The following points were furnished me by Mr. A. J. Norris, Chief 

 Consulting Engineer to the Peruvian Corporation: In 1909 a bridge 

 gang of thirty North Americans was taken to Purhuay for work on the 

 Central railway. Their camps and beds were all new and clean. 

 They had no occasion to dig up the soil, being engaged in bridge work, 

 and had practically no occasion to get into the herbage or other vege- 

 tation along the river bed. Within hardly more than a week twenty- 

 nine of the thirty contracted verruga fever. The camp was then 

 changed to Chosica, which is just below the edge of the verruga district, 

 and new men were put on the Purhuay work but camped at Chosica, 

 returning there every evening for the night. No cases appeared among 

 these new men.. 



In 1906, at San Bartolome, which is in the verruga district on the 



