TRANSACTIONS OF SECTION D, 809 



TUESDAY, SEPTEMBISR 19. 



The following Papers were read : — 



1. On Certain Gregarinidce, and the possible connection of Allied Forms 

 with Tissue Changes in Man. By Charles H. Cattle, M.D., Al.B.G.P., 

 and James Millar, M.D. 



After giving a general review of the classification of the protozoa, the writers 

 pointed out that they were chiefly interested in the sporozoa, and that because of 

 their parasitic habits, especially in the bodies of the higher vertebrates. There 

 was much still unknown of the habits, life-history, and distribution of these 

 organisms, and the co-operation of biologists with medical men was invited for 

 the elucidation of many unsettled questions. One of these was how far certain 

 of the sporozoa, at present classified as distinct species and genera, were to be 

 properly so considered, and how far some of them were really alternative forms 

 of the same organism modified by change of host and other external influences. 



A detailed description was given of tfie authors' own observations on the 

 development of the coccidium oviforme of the rabbit. On the authority of 

 L. Pfeifler ' it was stated that in the body of its host, the coccidium multiplies 

 by means of a most prolific zoospore formation, while in external media it forms 

 lasting spores. The authors took some material derived from the rabbit's gall- 

 bladder, containing coccidia, and watched the development of the parasite under 

 different external conditions. When the specimens were first observed, the 

 granular protoplasm, contained in the coccidium capsule, had already contracted 

 into a rounded mass, lying either in the centi-e, or somewhat to one end. The 

 first specimen to show further change was one kept in ordinary water at the 

 temperature of the air, and imsealed so that there was free access of air to it. 

 "Within a .space of two days the granular ball had divided into two, and in some 

 instances into four portions. Sometimes the final division was into three portions 

 instead of four. As an ultimate result of the segmentation the parent coccidium 

 came to contain three or four sporoblasts, each containing one or two (generally 

 two) refractile translucent bodies (spores) and some granular matter, the so-called 

 nucleus de reliquat. The authors entirely failed to see the C-shaped rod with 

 thickened ends, which has been described - as lying within the sporoblasts. At a 

 later stage individuals were met with in which the sporoblasts could be seen 

 making their way out of the containing capsule and floating free in the surround- 

 ing fluid. The authors believe this is the first time this phenomenon has been 

 actually observed ; but they feel some doubt as to whether what they saw was 

 entirely sponianeous, or had been assisted by the pressure of the cover-glass used 

 in mounting the specimen on the slide. Probably under ordinary circumstances 

 the spores remain unchanged for an indefinite time, and only undergo further 

 change when they reach the interior of a new host. Ultimately they give origin 

 to amoeboid germs which penetrate into epithelial cells. The authors regard 

 the interior of the tissue-cells as the necessary abode of tlie young forms of all 

 sporozoa ; and if this opinion is correct, they see great difficulties in the way of 

 artificial cultivation of coccidia or any other true ceU-parasite. 



The tissue-changes in the rabbit's liver due to a known parasite (the coccidium) 

 were stated to bear a close resemblance to those which constitute cancer in the 

 human subject. In the latter bodies have of late years been described and which 

 by many observers are considered as protozoa. The authors showed by means of 

 lantern slides the structure of these latter bodies as they had found them in their 

 preparations. The reasons for looking upon them as parasites were briefly — 

 1. The cell-growth, which is the fundamental change in cancer, is quite ana- 

 logous to the changes produced in animal tissues by known parasites. 2. They 



' UntersucTixm/jen iiher den Krehs, Jena, 1893. 

 ' Leuckart, The Parasites of Man, 1886. 



