iroSEMA-DlSEASE. 7 



bears some relation to the peritrophic membranes (Pmh). Outside 

 the basement membrane is the muscular portion of the stomach wall 

 consisting of three (White, 1918) muscular layers (PI. II, D; and PI. 

 Ill, 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 diEferentiated 

 so easily by staining, are not shown; they are found toward the base of the cells reaching the basement 

 membrane (-BJ/), 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 laj'er and a middle circular one. (Author's illustration.) 



epithelial cells (fig. 2, C, EptJi) and a basement membrane (BM), hut no 

 pronounced intima. The function attributed to these tubules is one 

 comparable in a measure to that of the kidneys of the vertebrates. 



CAUSE OP 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 fomid to be teeming 

 with the parasites. A second colony was then similarly fed on Decern- 



