754 THE MICROSPORIDIA 



Aut illae pedibus connexae ad limina pendent, 

 Aut intus clausis cunctantur in aedibus, omnes 

 Ignavaeque fame et contracto frigore pigrae." 



[Infection takes place by the contaminative method and may be trans- 

 mitted through the agency of infected foods or of. living infected bees. 

 Foraging bees infected by ingesting food containing the spore and " parasite- 

 carriers " are the most important agents of infection (Graham Smith and 

 Bullamore). 



[The main alimentary tract of the bee, particularly the chyle stomach 

 and intestine, are the chief parts infected. The gut diverticula appear to 

 be free from parasites, but as the Nosema may be found in the hsemocoelic 

 fluid, the parasite may occasionally invade other organs (Fantham and 

 Porter). It is at present doubtful whether hereditary infection occurs as 

 is the case with Nosema bombycis in silkworms (vide supra). 



[The spores of Nosema apis occur as oval, highly refractile bodies 2 4/x 

 in diameter and 4-6/* in length. Frequently they are found lying between 

 the cells of the gut wall and in the earlier stages these cells are distended with 

 the parasites. 



[Technique. For microscopical examination small portions from different parts 

 of the alimentary canal should be teased out in a drop of water and mounted under 

 a cover-glass. As fixatives, osmic acid vapour followed by absolute alcohol, or 

 acetic-perchloride solution may be used. The most useful stains are Giemsa's 

 solution or haematoxylin. Sections give very disappointing results. For the 

 extrusion of the polar filament treatment with iodine water or dilute acetic acid 

 are recommended. 



[Life history. Spores of the parasite, swallowed with food or drink by the bee, 

 give rise each to an amoeboid parasite or planont which either enters an epithelial 

 cell of the gut or reaches the hsemocoele. In either case it becomes rounded, feeds, 

 grows and then commences to multiply. The meront, as the parasite is described 

 at this stage, divides by binary fission producing clusters or chains, each daughter 

 meront being ultimately uninucleate. 



[The multiplicative stage is followed by the second or propagative stage sporo- 

 gony. The full grown meront becomes the sporont or pansporoblast which undergoes 

 complicated nuclear changes whereby five nuclei are ultimately produced. The 

 sporoblast forms two vacuoles, an anterior one called the polar capsule and a posterior 

 vacuole in which the polar filament is coiled. The secretion of the sporocyst con- 

 verts the sporoblast into the spore (Fantham). ] 



Among other species of Microsporidia the following may be mentioned : Nosema 

 ovoideum, a parasite of Motella tricirrata and of Cepola rubescens : Nosema bryzotdes, 

 found in certain Bryozoa. Lutz and Splendore have described several species of 

 Microsporidia in the Lepidoptera, in different insects and in a Cyprinodont fish. 

 Simond has found a Nosema in a mosquito (Stegomyia fasciata) : this parasite seems 

 to be identical with Myxococcidium stegomyice, erroneously described by Beyer and 

 by Parker and Pothier as the cause of yellow fever. 



SECTION II. THE MYXOSPORIDIA. 



The Myxosporidia are found as parasites in fish, reptiles, arthropods, etc. 

 They inhabit the skin, gills and internal organs : the nervous system appears 

 to be the only part of the body never infected. 



Jaboulay is of opinion that cancer in man is due to a Myxosporidium, the 

 source of infection being salads, molluscs, fish or unsuitable drinking water. 



Detection of Myxosporidia in fish. The parasites should be looked for in 

 the small prominent pustules which develop on the integuments, in the blood 

 cysts which form on all the branches of the splenic artery (in tench), in the 



