18 



The disease spreads somelimes all over the apiary, mainly through 

 bee-excrements which are full of Nosema spores. A such atTected 

 eolony is beyond rescue according to Z änder. The hive is usually 

 mudd} r from excrements, and sick bees crawl around in the mud 

 with swollen abdomens unable to fly. The stench from such a 

 colony is dreadful. 



This is the usual way in which the disease manifests itself dur- 

 ing winter. In the spring bee-paralysis often affects one or several 

 colonies in the apiary. The symptoms of bee-paralysis are some- 

 limes similar to those of microsporidiosis, although voiding of ex- 

 crements never takes place when the bees are affected with para- 

 lysis. On account of more or less superficial similarities between 

 the two diseases Zander concluded that Nosema was the cause of 

 the paralysis as well. In the spring the young bees are supposed 

 lo contract the disease by coming in contact with the sources of 

 infection formed during winter by the excrements of the old bees 

 died from microsporidiosis. He assumes that the symptoms of the 

 disease are the same in winter and in spring: »Die Bienen fliegen 

 voller Aufregung aus dem Stock, fallen auf den Boden, unfähig 

 sich wieder zu erheben, rennen sie umher oder kreisen auf dem 

 Riicken liegend. Schliesslich sammeln sie sich in kleinen Haufen 

 an Grashalmen etc. an, um noch längerer oder kiirzerer Zeit zu 

 sterben» (28, pag. 16). 



This attempt of explaining the cause of paralysis encounters cer- 

 tain dilficulties some of which are indicated by Zander himself. 

 While the bees which die during winter from microsporidiosis have 

 ventriculus filled to capacity with Nosema spores often no trace of 

 spores is found in the intestines of the young bees which die from 

 paralysis in spring. That these bees nevertheless lodge the para- 

 sites which cause Iheir death by being present in the intestinal 

 wall nas, according to Zander, been proven by the following ex- 

 periment. If such bees are kept in incubators from 8—14 days 

 they will die from microsporidiosis, and ventriculus will then be 

 found to be full of Nosema spores. However, this experiment shows 

 nötning of the sort! One is just as entitled to assume contamina- 

 tion of bees free from Nosema by some infected ones, the two cate- 

 gories having been mixed before the experiment was begun, for the 

 simple reason, that it is impossible to distinguish between them in 

 the early stage of the disease without killing and examining the 

 bees under the microscope. 



