147 



main presents a picture of Nosenia apis as a comparatively harm- 

 less associate of bees. This is not, however, invariably the case, as 

 is shown in subsequent records, and our experience has suggested 

 that much depends upon other factors of the environment. In a 

 number of cases in which we kept bees in unfavourable conditions 

 or in which the natural circumstances were adverse, e.g. as regards 

 weather, we found that dysentery and a significantly high mortality 

 were associated with the presence of Nosema apis in the bees. In 

 particular we have over a series of years kept bees in single frame 

 observation hives, and invariably during winter, when these bees 

 were kept at a living room temperature by day and allowed to 

 feed freely — the temperature falling naturally during the night, — 

 dysentery developed, accompanied by a high mortality. In a 

 number of such cases Nosema has been found in a high proportion 

 of the bees. We have no experimental evidence in these cases as 

 to how far the presence of Nosema in the unfavourable circum- 

 stances here recorded is responsible for the dysentery and rapid 

 mortality, but on the other hand it has been clear to us that once 

 dysentery was present in a Nosema infected stock, the numbers of 

 actually infected bees were much greater than in those cases 

 where Nosema was present, but dysentery was not observable. 



ISLE-OF-WlGHT DISEASE AND NOSEMA DISEASE. 



Records of Concurrent History of Isle-of- Wight Disease and 

 Nosema Disease. — We have now to record cases of Nosema 

 disease with which there were associated the symptoms ordinarily 

 regarded as diagnostic of Isle-of-Wight disease, or in which 

 Nosema appeared to be affecting the stock in an adverse manner. 



No. 7. In the summer of 1916 a frame of black bees removed 

 from an experimental stock suffering from Isle-of-Wight disease 

 was placed in a one frame observation hive, supplied with an 

 Italian queen, and removed to another area over 20 miles away. 

 The parent experimental stock had no history of Nosema infection, 

 and was believed to be free of this parasite. At the time of the 

 institution of the experiment now being recorded the weather was 

 unfavourable, and the bees both in the parent stock and in the 

 observation hive were exhibiting dysenteric symptoms and crawling 

 when opportunity offered. The result was that the queen ceased 

 laying. With an improvement in the weather both crawling and 

 dysentery diminished, but the number of bees was now very small. 

 A fresh frame of bees from the same source was introduced to the 

 experimental hive, and after temporary confinement of the queen in 

 a cage, she was released, accepted, and began to lay. The 

 dysentery at this period had almost disappeared. 



On the 30th July there was sealed brood on both sides of the 

 frame. 



On this date a flying bee taken on the alighting board about 

 to enter the hive was found to be infected with Nosema. The 

 chyle stomach was heavily parasitised, and free spore clusters were 

 abundant in the colon. Further examinations were repeatedly 

 made of both live and dead bees at this date, but in only one 



