66 The Isle of Wight Bee Disease. 



genus, viz., Noscma (Glugea) bonibycis, causes the disease 

 known as Pebrine among silkworms, which was so thoroughly 

 investigated by Pasteur. Nosema is placed in that section of 

 the Protozoa known as the Microsporidia, and for this reason 

 the disease has been referred to under the somewhat cumbrous 

 title of " Microsporidiosis." Another and more euphonious 

 name is " Nosema disease," which has been used in America. 

 It is a translation of its German equivalent, " Nosema Seuche," 

 which was given l)y Zander. Infection of the bee usually 

 takes place by means of spores, which contaminate the food 

 and water. A single spore of Nusema is a minyte oval body 

 3^oV(T of 8-11 inch in length, enclosed in a tough resistant 

 membrane. On being swallowed by the bee, the spore passes 

 into the mid-gut or chyle stomach of the latter. The digestive 

 secretions within the chyle stomach stimulate the spore, and a 

 minute amoeboid body known as a planont (meaning a 

 wanderer) emerges therefrom. Each planont may divide and 

 produce daughter planonts, which in their turn can divide 

 again. By this means the parasite adds greatlj^ to its numbers. 

 The planonts wander over the inner surface of the chyle 

 stomach, and eventually penetrate into the cells forming its 

 lining epithelium. Occasionally, however, they make their 

 way directly through the gut wall and pass into the body 

 cavity. When once within the epithelial cells the planonts 

 become passive, rounded in form, and growing at their expense 

 ultimately weaken the wall of the gut. Each planont sooner 

 or later divides into two, four, or even more bodies, which are 

 known as meronts (meaning portions or segments). In this 

 manner the Nosema furthei' increases its numtjers, and it is at 

 this stage the organism is most fatal to the bee. 



The meronts, in their turn, may divide and form daughter 

 meronts. After a period of growth, each meront ordinarily 

 undergoes a series of changes which resiilt in its giving rise to 

 a spore. The epithelial cells containing the spores are shed 

 into the digestive cavity, where they rupture, thus liberating 

 the spores into the gut. Ultimately the spores pass to the 

 exterior in the faeces of the bee, and are then liable to con- 

 taminate the food and water. Along with the latter they can 

 enter the digestive system of healthy bees, and initiate afresh 

 the life-history just described. It is noteworthy that the 

 planonts and meronts, if discharged from the alimentary 

 canal in the faeces, perish immediately. On the other hand 

 the spores, in virtue of their resistant membrane, are able to 

 withstand adverse conditions until they reach a new host bee — 

 they are specially adapted to ensure the continuance of the race. 



The parasite is usually restricted to the digestive system of 

 the adnlt l)ee. It attacks the chyle stomacl) and intestine more 



