144 



sufficient stores for wintering. Throughout the whole period of 

 observation and experiment no signs of disease have ever been 

 noted, and the infection with Nosema appears to have disappeared 

 about the time of swarming. 



Summary. — Infection with Nosema appears to have occurred 

 naturally from an adjacent stock (No. 31, p. 16) within the period 

 of one month, and to have been maintained for two months; sub- 

 sequent to this date parasites were not found, and it should be 

 noted that in the adjacent stock at this time the same feature 

 occurred. The infection while present was not accompanied by- 

 dysentery or any other disease symptoms, and during its presence 

 increase of the stock was maintained. The infection while it 

 lasted could not be regarded as materially affecting the prosperity 

 of the colony. The success of the stock was not absolute, since 

 only a limited amount of surplus stores was obtained, but we 

 cannot believe that the presence of Nosema was more than a minor 

 cause of this ; even in relatively unfavourable circumstances the 

 parasite failed to spread within the stock. 



No. 3. Natural Infection of a Nucleus. — In February 1918 a 

 small one frame nucleus of bees was established with a view to 

 experiment. They were tested for the presence of Nosema, five 

 bees being examined individually by microscopic search and 

 eighteen by having their chyle stomachs pulped and searched. No 

 trace of the parasite was observed. 



Prior to any experimental use of this nucleus, the bees, during 

 a short period in the middle of the day upon 22nd March, obtained 

 access to a hive containing Nosema infected frames, left open 

 temporarily by an attendant. The source of the infection was 

 forthwith removed. 



On 22nd April eight bees of the nucleus were examined, and 

 all were found to be infected with Nosema. Again on i6th May 

 five young bees were tested and three found infected. Again on 

 nth June seven dead bees from this stock were examined and 

 Nosema was found in two. On Sth July three live bees were 

 examined and no Nosema found. 



Towards the end of May the queen was lost through the intro- 

 duction of a small lot of bees intended to strengthen the nucleus. 

 She was replaced by a queen surviving from an Isle-of-Wight 

 diseased stock. Notwithstanding the presence of the parasite the 

 nucleus continued to build up, so that in the beginning of August 

 the bees were covering nine frames with brood upon seven. During 

 the season, from March till August, whilst Nosema was being 

 demonstrated in the stock, there never were any signs of dysentery 

 nor of Isle-of-Wight disease. This small colony became the 

 subject of another experiment in which there was no further history 

 of Nosema. 



No. 4. Failure to infect by Means of Bees from Colonies 

 previously harbouring Nosema Apis.— On the i8th June a nucleus 

 (No. 14) consisting of four frames of bees, including the queen, was 

 taken from stock No. 31 and a frame of brood and stores from 

 No. 32. These were placed in a newly disinfected and painted 



