228 SOME MINUTE ANIMAL PARASITES 



excretory organs or Malpighian tubes (Fig. 42, m.t.) 

 open into the chyle stomach, but are rarely infected. 

 The hind-gut or large intestine (Fig. 42, Li.) is very 

 seldom parasitized, although its contents may be 

 almost white from the spores contained in it, and 

 under certain conditions, it may contain a fair number 

 of young stages of the parasite, which have come 

 from shed infected cells of the chyle stomach. 



All the organs of workers, drones, and queens have 

 been examined in detail for stages of the parasite, 

 but up to the present few developmental forms have 

 been found in them. Again, eggs, larvae (both freshly 

 hatched and of all ages), pupae, and young bees, 

 have also been examined. So far as the ovaries of 

 the queen are concerned, while a few planonts have 

 been found very rarely, no further development has 

 been obtained. Larvae undoubtedly have contained 

 not only young stages, but all stages of the life-cycle 

 of the parasite. But there is always the possibility 

 of larvae acquiring the parasites with the food supplied 

 them by the nursing- bees or from the " nurses " them- 

 selves, and consequently it is impossible at present 

 to affirm that there is hereditary infection. 



It is far otherwise with the Nosema of the silk- 

 worm. Pasteur's famous method of exterminating 

 pebrine was based on the infection of the eggs by 

 Nosema bombycis, acquired from one or other parent. 

 The female moths were so enclosed that the eggs 

 were laid on a pad of cloth. Moths and eggs were 

 given a serial number. The dead male and female 

 were then crushed in water, and the filtered emulsion 

 examined microscopically. If any spores of N. bom- 



