Journal of Applied Microscopy. 



41 



the alcohol. If it is desired to remove 

 all the mercury from the {issues, the 

 tincture of iodine should be added from 

 time to time until the iodine is no longer 

 removed from the alcohol, which of 

 course is indicated by the fact that the 

 alcohol does not loose the iodine color, 

 that is, retains the brownish color. The 

 following suggestions may be made as 

 to which of the three hardening reagents 

 to select for any given piece of tissue. 



If it is desired to make a bacteriolo- 

 gical examination, as well as a patholo- 

 gical diagnosis of any given tissue, alco- 

 hol should be selected as the hardening 

 fluid. 



If it is desired to harden the tissues 

 rapidly and simply to determine the 

 nature of the tissue, formalin will 

 answer very well. 



If, on the other hand, it is desired to 

 make out the finer details of the pro- 

 toplasm and nuclei of the cellular ele- 

 ments of a given tissue, Zenker's fluid 

 should be used in preference to the other 

 two hardening reagents mentioned. 



University of Michigan. 



The Coccidium Oviforme. 



Joseph McFarland, M. D. 



Professor of Pathology and Bacteriology in the 



Medico-Chirurgieal College, Philadelphia. 



The epithelial cells of the livers and 

 intestines of the lower animals are not 

 infrequently occupied by intracellular 

 })arasites, known as coceidia. These 

 minute organisms have been found in 

 calves, mice, rats, cats, salamanders, 

 centipedes, cuttlefish, and snails, and 

 occasionally in man. In recent years 

 not a little literature has accumulated 

 upon the existence of rather similar 

 organisms in the epithelial cells of 

 carcinoma. The most common form is 

 the Coccidium oviforme of Leukhart, or 

 P. sorospermium cuniculi of Rivolta. This 

 parasite is chiefly found in the rabbit, 

 and has two principal seats of occur- 

 rence; first the liver, second the intes- 

 tines. A recent epidemic of the disease 

 which occurred in my laboratory 

 afforded excellent opportunity for study- 

 ing it, and the peculiar lesions it pro- 

 duces. The animals affected were young 

 rabbits, which became acutely ill with 

 prostration, nervous twitchings, diar- 

 rhoea, frothing at the mouth, and 

 apparently vomiting. Within twenty- 

 four hours the animals became moribund 

 and died in convulsions. 



Upon examining the bodies of these 

 animals, the livers were found much in- 

 creased in size, soft, dark-colored, hyper- 

 emic, and filled with small yellowish 

 nodes of rather firm consistence and 

 creamy contents. The nodules were 



distributed throughout the liver sub- 

 stance equally. In one or two cases there 

 seemed to bo more of them in the small 

 lobes than in the larger ones. They were 

 fairly uniform in size, the extremes of 

 variation being from a pin's head to a 

 pea. The naked eye appearance at the 

 first glance suggested tuberculosis, but 

 various differences were immediately 

 detected. The liver was deeply con- 

 gested, which is generally not the case 

 in tuberculosis. The nodes contained 

 softened material, while tubercles are 

 generally firm, and the nodules were dis- 

 creet, not seeming to tend to form 

 cheesy masses. "When the contents of 

 one of the nodules was examined micro- 

 scopically, it was found to contain large 

 numbers of the adult egg-shaped, per- 

 manent, encysted form of the parasite. 

 The adult parasites are found in the 

 softened contents of the parasitic cysts 

 in the intestinal contents, and in con- 

 sequence in the faeces. They are oval, 

 egg-shaped, transparent bodies with 

 granular contents, and measure from 1.^ 

 to 25 by 30 to 40/<. They are surrounded 

 by a very delicate outer, and a very 

 strong, double-contoured, shining inner 

 membrane, with a small opening or 

 micropyle at one end. The granular con- 

 tents are usually of an oval or circular 

 form, and contain a paler spot like a 

 nucleus. Sometimes the contents of the 

 cyst rolls itself together, leaving the 

 poles entirely empty. The adult form 

 bears a striking resemblance to the eggs 

 of some of the intestinal parasites, espe- 

 cially the Distoma lanceolatum, so that 

 in spite of our now extended knowledge 

 upon the parasites, there are some who 

 still regard it as a stage in the develop- 

 ment of soine worm. 



"When the cyst contents containing- 

 these adult parasites are fed to rabbits 

 or injected into rabbits, or when rab- 

 bits are fed upon the livers of diseased 

 animals, no infection takes place because 

 the coceidia have very poor resisting- 

 powers, and are destroyed in the stom- 

 ach. The propagation of the disease 

 requires that the parasites shall be dis- 

 charged from the body, and remain in 

 moist soil. "When this happens a series 

 of changes, presumably similar to those 

 seen in the hanging drop specimens 

 which can be conveniently studied in 

 the laboratory, takes place. 



The central mass of granular mat- 

 ter is seen to divide itself into two and 

 then into four, first round, and then 

 elliptical fragments, each of which is 

 surrounded by a membrane. Each of 

 these can be properly called a spore, and 

 in each two falciform embryos develop. 

 The complete cycle occurs in from one 

 to two weeks. According to the view of 

 Rieck, when the spores are devoured 



