THE MICROSPORIDIA 753 



[The nucleus of the sporont (sporoblast) buds off three small nuclei, two of which 

 form the sporocyst and the third is concerned with the polar capsule. The principal 

 nucleus remains as the nucleus of the amosbula. The protoplasm probably also 

 divides. The sporocyst when formed is a tough capsule which though produced 

 by two cells does not show any indication of its two-fold origin. The spore is 

 egg-shaped the anterior end being the narrower. The single polar capsule is of 

 relatively large size and contains a very long filament. The amcebula occupies 

 the middle of the spore and appears to encircle the axial polar capsule. The amcebula 

 has at first a single nucleus which subsequently divides into two then into four. 



[When the spore germinates in the intestine of a new host the polar filament is 

 extruded and the amcebula escapes by the pore at the anterior end. The amcebula 

 emerges from the spore with two nuclei leaving the other two in the sporocyst. The 

 two nuclei fuse to form a synkaryon and the now uninucleate amoebula initiates the 

 generation of planonts (Stempell). 



[Hereditary infection is effected by the penetration of the parasite into the ovary 

 and the formation of spores within the ovum itself. Hence not only may the silk- 

 worm be infected by ingesting spores of the parasite but the newly- hatched silkworms 

 may already be infected. This transmission of infection through the egg is with 

 the possible exception of the parasite of Texas fever unique among the Sporozoa. ] 



FIG. 355. Nosema bombycis. B, masses of Microsporidia in a follicle of 

 the testis of a silkworm : S, mature spores : S'. immature spores. (After 

 Balbiani.) 



The detection of the parasites. The Microsporidia are highly resistant to 

 the action of chemical reagents, and can be best seen in the fresh state, 

 unstained, with an high power dry objective. They may be stained by 

 Vlacovich's method : treat with a 32 per cent, solution of potash for 48 hours, 

 then with Gram's solution, and examine in a drop of glacial acetic acid : the 

 parasites are stained violet. 



2. Nosema apis. 



[An epizootic disease of bees 1 which on account of the ravages it has 

 caused during the past few years among the bees in the Isle of Wight has 

 popularly become known as the Isle of Wight disease has been shown by 

 Fantham and Porter to be due a microsporidian parasite of the genus Nosema 

 Nosema apis. The disease however is widely spread and is more suitably 

 described as Microsporidiosis of bees. 



[The symptoms of bee disease which however seem to be subject to considerable 

 variation are thus described by Virgil: 2 



" Si vero, quoniam casus apibus quoque nostros 

 Vita tulit, tristi languebunt corpora morbo 

 Quod jam non dubiis poteris cognoscere signis : 

 Continue est aegris alius color; horrida voltum 

 Deformat macies ; turn corpora luce carentum 

 Exportant tectis et tristia funera ducunt ; 



f 1 See Supplement No. 8 to The Journal of the Board of Agriculture, Vol. xix. No. 2. 

 May 1912.] 



[ 2 P. Vergili Maronia, Georgicon, Liber Quartus.] 



SB 



