NOSEMA-DISEAS^. 7 
bears some relation to the peritrophic membranes (Prrib), Outside 
the basement membrane is the muscular portion of the stomach wall 
consisting of three (White, 1918) muscular layers (PL II, D; and PL 
III, L). The outer and inner ones are made up of longitudinal and 
the middle one of circular fibers (fig. 3). Each layer is made up of a 
single layer of branched fibers. 
Digestion and absorption, comparable to some extent to those 
obtaining in the human stomach, are functions which have been 
attributed to the stomach of the bee. 
The Malpighian tubules {fig. 2, G Mai) empty into the alimentary 
tract at or very near the juncture of the stomach and small intestine. 
Microscopically their structure is seen to consist of a single layer of 
Fig. 3»— Longitudinal section of stomach of honeybee showing infection with Nosema apis: ep, Epithelial 
portion, containing the spores of the parasite stained black. (The younger parasites, not differentiated 
so easily by staining, are not shown; they are found toward the base of the cells reaching the basement 
membrane (BM), but do not extend beyond it. Younger spores sometimes show an unstained area at 
one end and occasionally at both ends.) m, muscular portion of stomach wall showing an outer and an 
inner longitudinal muscular layer and a middle circular one. (Author's illustration.) 
epithelial cells (fig. 2, C, Eptli) and a basement membrane (BM), hut no 
pronounced intirha. The function attributed to these tubules is one 
comparable in a measure to that of the kidneys of the vertebrates. 
CAUSE OF NOSEMA-DISEASE. 
THE EXCITING CAUSE. 
On December 4, 1856, Donhoff (1857, August) inoculated a colony 
of bees with the oval bodies he had found in the stomachs of adult 
bees. The inoculation was made by feeding the colony the crushed 
stomachs of the infected bees in a honey suspension diluted with 
water. Upon examining stomachs from adult bees taken from the 
inoculated colony in eight days following the inoculation no spores 
were observed. In 11 days, however, they were found to be teeming 
with the parasites. A second colony was then similarly fed on Decern- 
