Journal of Applied Microscopy. 



43 



infection for many montlis, or even a 

 year or two, no intracellular parasites 

 can be found at all. Still later, the con- 

 traction of the connective tissue capsules 

 diminishes the size of the cysts so that 

 they often do not exceed the size of pin- 

 heads or millet seed. 



The developmental cycle described by 

 Pfeiffer can only be seen in the acute 

 cases previously described. The falci- 

 form embryos are found with consider- 

 able difficulty; one may have to search 

 over many fields of the microscope, in 

 order to find any that are distinctly visi- 

 ble. These embryos seem to be distinctly 

 motile, i. e., ameboid. The intestinal 

 infection which in the rabbit is less fre- 

 quent than the hepatic form, may take 

 the form of localized patches, or may 

 affect the epithelium of the intestines 

 from end to end. In the coccidiosis of 

 mice, the intestinal infection is quite a 

 marked feature, the whole length of the 

 intestine being generally involved. In 

 cases of local infection the infiamed 

 area is thickened, rather pale in color, 

 and on microscopic section shows 

 exactly the same character of intracel- 

 lular parasitism seen in the bile ducts. 

 Leukhart gave to the intestinal form of 

 coccidiosis the name coccidia perforans, 

 supposing that this parasite differed 

 from the hepatic form. It seems to be 

 rather smaller in size, measuring 13 to 

 20X24 to 35/<, and is characterized by 

 less compressed form, a more rapid 

 development of the spores (three or four 

 days), and the formation ol a permanent 

 body. It is a question whether the two 

 forms differ, especially when they occur 

 simultaneously in the same host. Kruse 

 is of the opinion that the differences are 

 due to the organ affected, the seat of 

 the disease. A marked difference in the 

 aeration of the parasites of course exists, 

 those in the liver receiving less air than 

 those in the intestine. 



Sheridan Delepine, investigating the 

 developmental cycle described by Leuk- 

 hart, was able to trace all of the devel- 

 opmental stages in the parasite con- 

 tained in moist sand, and was able to 

 infect animals by making them ingest 

 the parasites in the spore-containing 

 stage. 



The coccidia are classified among the 

 lower orders of the protozoa and differ 

 from the gregarines by completing their 

 life cycle within the cell, instead of leav- 

 ing it to continue a free existence. They 

 are also devoid of the worm-like shape 

 of the gregarines, and have not their 

 bodies divided into three layers. The 

 protoplasm is also more uniform, and 

 the ectosarc is thicker. They are not 

 motile, and the symbiosis, which is so 

 universal among the gregarines, rarely 

 if ever takes place among the coccidia. 



Their reproduction takes place solely 

 through the formation of spores, hence 

 they belong to that group of minute ani- 

 mal organisms known as the sporozoa. 

 This sporulation, which characterizes 

 them, has already been mentioned as 

 occurring in a direct or indirect form; 

 in either case the outcome of the pro- 

 cess is the formation of sickle-shaped 

 or serpentine, inotile germs. The pro- 

 ducts of direct and indirect sporulation 

 differ in size and shape. The probability 

 is that the conversion of the whole 

 coccidium into a spore is a provision of 

 nature for the distribution of the animal 

 from individual to individual, while the 

 indirect sporulation, or formation of 

 numerous sickle-shaped bodies in its 

 interior, takes place in order to effect 

 the infection of the individual cells of 

 the individual host. The pathogenic 

 power of the coccidia, as seen from this 

 disease of rabbits which we have dwelt 

 upon, is undoubted, and the peculiarity 

 of the hepatic nodes has suggested to 

 many that cancer may in all probability 

 result from coccidial affection of the 

 glandular, epithelial cells. The litera- 

 ture upon the relation of the sporozoa 

 to carcinoma has attained voluminous) 

 proportions in the last three or four 

 years, so that any kind of a synopsis ot 

 it would be wearying. No proofs have 

 been brought forward by those who 

 have inclined to the micro-organismal 

 theory of cancer. 



One important characteristic or the 

 coccidial infections, which separates 

 them very clearly from all the carci- 

 nomas, is the fact that the epithelial 

 infection which takes place is always 

 kept within bounds by the basement 

 membrane, and that under no circum- 

 stances do the epithelial cells gain 

 entrance into the interstices of the tis- 

 sue. Could we find occasional illustration 

 of this tissue invasion by the epithelial 

 cells in coccidiosis, the homology 

 between it and cancer would of course 

 at once be evident. In its absence, 

 however, the coccidial diseases become 

 little more than infectious catarrhal 

 infiammations, affecting the various 

 weaker surfaces of the body. 



Renal coccidiosis occasionally affects 

 man. The cases that occur in human 

 medicine are in their symptomatology 

 not unlike those of the lower animals. 

 In a case reported by Silcock, the illness 

 came on about six weeks before admis- 

 sion to the hospital and was character- 

 ized by pains in the limbs, nausea, occa- 

 sional sickness, slight diarrhoea, tender- 

 ness over the liver and spleen, tempera- 

 ture ranging between 101°F. and 103°F. 

 the whole set of symptoms being ushered 

 in with a chill. The urine was albumi- 

 nous, the hepatic and splenic dullnesses 



