94 DISEASES. 



fall of 1859 and spring of 1860, I have arrived at 

 the conclusion that what has been called the dry foul 

 brood is but a condition of the moist, or is chilled 

 brood simply left remaining in the cells, and becom- 

 ing mummied, which is a thing of common occur- 

 rence in hives that are not strong. 



MICROSCOPIC EXAMINATIONS. 



I am indebted to Dr. Harkness, of Sacramento 

 City, for his kindness in making numerous micro- 

 scopic examinations of specimens of brood combs, 

 submitted to him at different times during the months 

 of March, April, and May, 1860. The following in- 

 teresting letter gives the result of his examinations : 



MR. J. S. HARBISON 



Dear Sir : Having made careful microsopic examination of 

 the samples of healthy and diseased brood combs placed in 

 my hands by you, I find the following conditions to exist ? First, 

 in all the samples of healthy brood, I find the cocoon surround- 

 ing each pupa or young bee, whether finished or only partly so, 

 to be constructed with great regularity, the threads of each 

 being arranged in the same relative position, forming a regular 

 system of delicate net-work. Second, in the samples containing 

 diseased brood, I find, in most cases, that death has occurred 

 while the pupa was in the act of forming its cocoon, as I find 

 them constructed with great irregularity, and in an unfinished 

 state. In some of the samples, however, I find cells interspersed 

 in which the larva has entirely disappeared, leaving a residiuum 

 of dark, inorganic matter, emitting a foul and disagreeable odor. 

 Upon examining the cocoon of such under the microscope, I 

 find that it is complete in texture and finish, showing that 



