26 BULLETIN 780, U. S. DEPARTMENT OF AGRICULTUKB. 



of the other colonies of the apiary (Table IV, colonies numbered 36, 

 50, 66, 68, and 82). 



The results obtained indicate, therefore, that by inserting combs 

 from Nosema-infected colonies, as was done in experiment No. 2, the 

 infection is not transmitted appreciably. An explanation for this is 

 easily seen from results recorded throughout the present paper. 

 Further experiments on the point are summarized in Table XXVI. 



EXPERIMENT NO. 3. 



In this experiment 7 colonies free from Nosema infectiop were 

 inoculated by feeding them sirup to which Nosema apis had been 

 added. The bees from which the parasites were obtained for this 

 experiment were from various sources (p. 12), They had been dead 

 and drying in the laboratory at room temperature for at least three 

 months. All of the 7 colonies received the first inoculation feeding 

 on October 8. On each succeeding day for four days the feeding 

 was repeated. Each of the inoculated colonies of the experiment 

 was examined from time to time, but no Nosema-infected beea were 

 found. The final examination in connection with this experiment 

 was made on October 28. Out of 70 bees examined from the 7 

 colonies only onp Nosema-infected bee was foimd. The infec^on in 

 this instance probably did not result from the inoculations. 



In this experiment it is shown that Nosema apis drying in the 

 abdomen of bees at room temperature for three months does not 

 produce infection when fed to healthy bees. This result suggested 

 the interesting fact that the parasite of the bee resisted drying for a 

 comparatively short time only (see other experiments, p. 40). 



EXPERIMENT NO. 4. 



In experiment No. 4, four of the colonies used in experiment No. 3 

 were inoculated on October 29, 1912, with Nosema apis taken from 

 infected bees recently killed. Nine days after the inoculation sam- 

 ples of bees were exammed from each of the four colonies inoculated. 

 Nosema infection was found in nearly all of the bees examined.. 

 Two weeks after moculation 50 bees were examined from each of 

 the 4 colonies. All of the 200 bees were found to be infected. At 

 the end of three weeks a shnilar condition prevailed. On DecemT 

 ber 16, 48 days after inoculation, all of the 4 inoculated colonies 

 were alive. A large number of bees were now found on the bottom 

 board of the hive. By this time the colonies had become very much 

 weakened. The bees were uneasy, the cluster being easily disturbed. 

 Dlirmg the foUowing week 1 of the colonies died out completely. 

 The remammg 3 were chloroformed. Another colony inoculated in 

 Novepaber gave like results, and died in January 1913 



Each of the 5 colonies of the experiment were four-framed nuclei. 

 As the inoculations were made late in the autumn there were no 



