lo Aug., 1911.] Dysentery, in Bees and Xosenia Apis. 551 



ones, during the summer, notwithstanding that Nosema-infected bees could 

 always be found ; only newly hatched bees were in every instance free 

 from the parasite. 



Dr. Maassen's experiments throw considerable doubt on the correctness 

 of Dr. Zander's view of the devastation resulting from Nosema apis. The 

 twenty-four badly infected stocks which wintered and built up well should 

 at least have shown large numbers of dead bees ; but they did not, and 

 only 10 per cent, of the infected colonies showed symptoms, and even 

 these recovered. 



After recounting a similar case which occurred in Bavaria, Dr. Hein 

 proceeds : — 



Other instances could be given of colonies in whicli Nosema was proved to 

 be present to a considerable degree at the beginning of winter without any notice- 

 able detrimental consequences r'^sulting in spring. There was no dysentery and 

 no mortality of large numbers of bees. In dealing here briefly with the Nosema 

 pest, as described by Dr. Zander, I cannot accept his repeated contention : " The 

 diseased bees are hopelessly doomed.' 



Amongst the lower animals, cjuite a number of parasites are known 

 which may be found in the majority of the individuals of a species in 

 very large numbers, and yet cannot be considered as disease-producing, 

 e.xcept in rare instances. We also know of animals which are inhabited 

 at the same time by a number of harmless parasites which are not con- 

 sidered disease-producing. But when such a parasite-infested animal 

 becomes weakened by starvation, cold, poor nourishment or disease, then 

 these parasites multiply rapidly and hasten death. They therefore can 

 only be looked upon as a secondary or contributing cause. 



The proof that Nosema always causes dysentery, and the destruction 

 of the affected bees, is entirely wanting. The few experiments made 

 by Dr. Zander are insufficient ; this is proved by Dr. Maassen's experi- 

 ments. The assiunption that May disease is caused by Nosema apis also 

 lacks experimental proof. Even though the parasite is regularly found 

 in great numbers in bees affected with May disease, its connexion with it, 

 as the cause, must be proved by conclusive e\[>eriments before it can be 

 accepted. 



From the point of view of Nosema apis, adopted by Dr. Zander, his 

 advice for combating the disease is totally inadequate. If the Nosema 

 parasite is, as Dr. Zander assumes, the primary cause of the disease, 

 the remedies recommended by him (except destruction by fire) can only 

 result in maintaining the source of infection, instead of removing it. By 

 transferring to clean hives, re-queening, and removal of combs, the diseased 

 bees are kept alive, and after a few hours or days again cause infection 

 of their new surroundings. 



The present aspect of the ([uestiou is that Nosema apis is a frequent 

 inhabitant of tees, and should certainly not be treated with indifference. 

 But, to consider the parasite as tlie primary cause of dysentery, as Dr. 

 Zander does, is not justifiable at present. Nosema is present in apiaries; 

 and, with Lni-es weakened by adverse conditions or irrational management, 

 it may get the upper hand through the bees losing their resistance to the 

 parasite. The experiments of Dr. Maassen and others demonstrate that 

 a good strong colony of bees can harbour the parasite for a long time, 

 without loss of vigour and productiveness. With natural, cleanly and 

 rational treatment, it should not be too difficult to maintain colonies in 

 such a condition that they are able to resist the apparently unaxoidahle 

 Nosema parasite. 



