2 BULLETIN 780, U. S. DEPARTMENT OE AGRICULTURE. 
from sacbrood. The disease is one, however, of considerable eco- 
nomic importance. 
The fact that Nosema-disease is not a new disease deserves em- 
phasis. The knowledge of the disease and its name only are of 
recent origin. Nosema-disease, like the brood diseases, has probably 
existed among bees longer than history records the keeping of bees 
by man. Since the disease is not a new one, fear regarding additional 
losses from it would not be justified. On the other hand, as we 
know of the disorder, we may entertain the hope that the losses due 
to it may now be lessened. 
Until 1909 the existence of Nosema infection among bees was not 
generally known to beekeepers, although it had been studied some- 
what by Donhoff (1857) about a half century earlier. Zander began 
his studies a decade ago and since the appearance of his first paper 
(1909) a number of investigators have made studies on the disorder. 
In the papers which have been written concerning the infection, 
widely differing views regarding certain points have been expressed. 
To discuss these different views would be to go beyond the scope of 
the present bulletin. 
The writer began the study of Nosema infection in 1910 following 
the demonstration by him that the disorder exists in the United 
States. In pursuing these investigations the object has been not 
to devise a treatment for the disease, but rather to ascertain such 
facts concerning the disorder that the beekeepers might be able to 
devise methods for its treatment with the assurance that they would 
be not only efficient but also economical. While there is yet much to 
be learned about the disease, this object has been fairly well attained. 
Relations which the results obtained bear to practical apiculture 
should be borne in mind, therefore, in reading the paper. 
During the studies the effect of the disease on colonies and on 
apiaries, the transmission of the disease, the resistance of the infecting 
germ to heat, drying, sunlight, fermentation, putrefaction, and dis- 
infectants, and the effect of drugs on the disease are among the 
problems which have been considered. 
An earlier paper (White, 1914) refers briefly to the nature of the 
results obtained from these studies. The present bulletin gives all 
the results obtained from them which are believed to be of direct 
practical value to the beekeeper or otherwise of particular interest 
to him. The nature of the bulletin is similar, therefore, to the one 
on sacbrood (White, 1917) recently published. 1 
1 As in the sacbrood paper, so in the present one, technical discussions have been purposely avoided. 
The semitechnical points which could not well be omitted are briefly explained in the sacbrood paper. 
Unless the reader is familiar with the nature of such investigations, the sacbrood bulletin will probably be 
found helpful in following the present one. 
