19 



Zander, aware of the diiHcullies, does nol dare to maintaiti Ihal 

 Nosema directly causes Ihe death of these bees. How the parasite 

 in an indirect way, however, accomplishes this is described by 

 Zander as follows (pag. 16): »Ich schliesse hieraus (that these bees 

 have no Nosema spores in the intestine), dass viele von den im 

 April und Mai absterbenden Bienen nicht an der Seuche selbst sterben, 

 sondern dnrch die Schmerzen, welche das Einbohren der Parasiten 

 in die Darmwand ihnen verursacht, ans den Stocken getrieben wer- 

 den und dureh Erkältung umkomnien.» 



The Zander theory, not only of the cause of paralysis but also 

 of the cause of dysentery, has been severely criticised by several 

 workers. The investigations of Maaszen (18, 19) have shown that 

 ihe presence of Nosema in the digestive tract of the honey-bee is a 

 very common phenomenon. It is hard, he says, to find any colony 

 in Gerniany that is entirely free from Nosema. Even bees with 

 great masses of Nosema in their intestines do not seem to be troubl- 

 ed by their presence. Maaszen wintered 30 colonies in the fall 

 1909 all of which were more or less infected with Nosema. Only 

 three colonies of the thirty showed symptoms of microsporidiosis 

 the following spring, and these soon recovered. Maaszen sums up 

 his wide experience in matters of bee-diseases in the concluding re- 

 mark that Nosema is not the terrible scourge that Zander held it 

 to be. Nosema may get the upper hand but only in such cases 

 where the bees are undergoing imperfect treatment, poor wintering, 

 unsuitable winter food etc. Similar views are held by Hein (13) 

 and, according to Bahr (3), by Nussbaumer and the Australian wor- 

 kers Brown, Laidlow, and Beuhne. 



That Nosema is not the cause of bee-paralysis is repeatedly held 

 forth b}^ Maaszen. Hein is equelly severe in his condemnation of 

 the Zander theory that bee-paralysis is due to the »erneute Aus- 

 briiche» of microsporidiosis. »Auch die Annahme, dass der Parasit 

 fur die Mai-und Junikrankheit verantwortlich gemacht werden kann, 

 ermangelt des experimentellen Nachweises», (pag. 85). BAHR(3)like- 

 wise admits that the cause of bee-paralysis is obscure. Practical 

 bee-keepers in Sweden seem also to doubt Zander's theory. Holm 

 (15j among others has in his handbook rejected this theory with 

 the remark that paralysis differs from dysentery in so far as para- 

 lysis seems to be a kind of constipation. Yet, he believes that a 

 specific organism occasions the disease, and that this organism 

 probably is present in the mouldy foodstuff, e. g. deteriorated pol- 



