THE SPOROZOA 



207 



As a general rule, however, the parasite selects some particular 

 organ, most often the excretory organs. 1 In Molluscs, especially, 

 the kidneys are the seat of these parasites more often than any 

 other organ (Fig. 48). In Arthropods this is less frequently the case, 

 but Eimeria nova, A. Schn., is found in the Malpighian tubules of 



....K 



FIG. 48. 



Klossia helicina, A. Schn., from the kidney of Helix hortensis, after Balbiani, from Wasie- 

 lewski. a, portion of a section of the kidney, showing normal epithelial cells containing con- 

 cretions (C), and enlarged epithelial cells containing the parasite (K) in various stages, b, cyst 

 of the Klossia containing sporoblasts. c, cyst with ripe spores, each enclosing four sporo- 

 zoites and a patch of residual protoplasm. 



Glomeris. In Vertebrates again the kidney is very often attacked ; 

 in other cases amongst this phylum it is not infrequently the 

 spleen, and even in a few instances the testis, which is selected 

 by Coccidian parasites never, however, the ovary ; so that in this 



the moth Tineola biseliella ; it attacks chiefly the fat -body, but may overrun also 

 the pericardial cells, oenocytes, Malpighian tubules, muscles, and epidermis ; it is 

 never found, however, in the gut - epithelium, nor does it penetrate the nervous 

 system, gonads, or imagiual discs. Another example is Adelea akidium, Leger, 

 parasitic upon various beetles (Akis spp. ; Olocrates abbreviate) ; it also attacks 

 the fat-body and the pericardial cells, but not any other organs. 



1 With regard to the question of the transport of the parasites within the body of 

 the host, Laveran [35] has drawn attention to an association between Coccidium 

 metchnikovi, Lav., and a Myxosporidian, Myxobolus ovtformis, Thel., in the gudgeon. 

 The Myxobolus in the liver, spleen, and kidney is found containing the Coccidium in 

 various phases of development, especially in the stage of cysts with spores, in which case 

 the Myxobolus usually contains no spores of its own. Free Coccidia not contained in 

 Myxosporidia are found only in the intestine. Laveran believes that the Coccidia 

 penetrate the Myxosporidia in the intestine, and that the latter then invade the 

 organs they affect, and transport the Coccidia with them. This view is contested by 

 Blanch ard ([30], p. 161). 



