NOSEMA-DISEASE. 9 



growth and multiplication of the parasite. The digestive fluids are 

 believed to assist in removing the spore coat. The liberated young 

 parasite finds its way to the walls of the' stomach and invades the 

 epithelial cells. Within this epithelial tissue it grows and multiphes 

 with great rapidity, giving rise finally to numerous spores. The cells 

 of the epithelium at times seem to become virtually filled with the 

 parasites (fig. 3; Pis. II and III). That portion of an epithelial 

 cell that is normally shed into the lumen of the stomach in case of 

 infection bears with it many spor-es. These are liberated gradually 

 from the fragments, become mixed with the partially digested food 

 of the stomach, and are carried onward first into the small and then 

 into the large intestine and finally pass out of the alimentary tract 

 with the excrement. Other bees ingesting these spores become 

 infected. This in brief is the life 

 cycle ^ through which the parasite 

 passes. 



Nosema apis reaches the tissues of 

 the bee by way of the alimentary 

 tract. In infecting the stomach the 

 parasite reaches the basement mem- 

 brane but does not penetrate it (Pis. 

 II and III). The muscular part of 

 the organ is therefore uninvolved 

 (fig. 3). Likewise when the infec- 

 tion is found in the Malpighian 

 tubules the germ does not proceed ^ _^ . , ^ 



111 r ' ^^®- 4.— Spores of Nosema apisas seen in a fresh 



beyond the basement membrane preparation,indicating their general oval form. 



(Pis. II and III). Furthermore the (Onginai.) 



germ does not infect (fig. 1) the pharynx (PJiy), the oesophagus {(E), 

 the honey sac (HS), the proventriculus {Pvent), the small intestine, or 

 the large intestine (Beet) — organs which possess a pronounced chitin- 

 ized intima. Infection with the parasite seems, therefore, to be con- 

 fined to the epithelium of the stomach and of the Malpighian tubules. 

 So far the writer has not encountered the germ in the blood, muscu- 

 lature, or any of the other tissues of the body. 



Nosema apis has not been cultivated in pure cultures by artificial 

 methods. The nature of the organism makes the accomplishment of 

 such a task at the present time especially difficult. Direct proof ob- 

 tained by the inoculation of bees with cultures of the parasite has 

 not, therefore, been obtained. Fortunately such direct proof is not 



1 Fantham and Porter (1911 and 1912) encountered a parasite in bees taken from colonies affected with 

 Isle of Wight disease which they have identified as Nosema apis. Their studies on the morphology of the 

 parasite are interesting. 



The morphology of Nosema apis and of Nosema bombycis are apparently quite similar and studies made 

 by Stempell (1909) on the latter parasite may be referred, to with profit in studying Nosema apis. 



103789— 19— Bull. 780 2 



