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18
The disease spreads sometimes all over the apiary, mainly through
bee-excrements which are full of Nosema spores. A such affected
colony is beyond rescue according to ZawpER. The hive is usually
muddy 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
to 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
Rücken liegend. Schliesslich sammeln sie sich in kleinen Haufen
an Grashalmen etc. an, um noch längerer oder kürzerer Zeit zu
sterben» (28, pag. 16).
This attempt of explaining the cause of paralysis encounters cer-
tain difficulties some of which are indicated by ZAanpeEr 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 their death by being present in the intestinal
wall has, 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
nothing 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.
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