.'JoG 



COCCIDIOSIS 01' THE INTESTINE IN THE GOAT 



Probably a 

 double type of 

 schizogony 



The micro- 

 gamelocyle 



ScHizoooNY Cycle 



No coccidiii in this stiif^e of (levelopmeiit iiave Ijccii found in any of tlie tissues. 

 Professor Minchin suggests that this stage takes place before any symptoms are seen 

 in the animal. From what I learu from Dr. Balfour, the second of the goats, of which 

 portions of the intestines and the fajces were sent home to me, appeared perfectly well, 

 though the coccidia were far advanced iu development in the sporogony stage. 



It would appear, however, that there is a schizogony of a double type, i.e. that at 

 a very early stage there is a differentiation of sex amongst the merozoites and that we get 

 macro- and micro-merozoites going on through several generations. 



I am led to this belief by the fact that in any one colony in the gut there is 

 always a great excess of one sex, and in several colonies I have found nothing but 

 microgametocytes, those nearer the lumen of the gut being older than those in the deeper 

 portions of the glands. 



Further, I find that in sections of liver from a rabbit infected with coccidiosis, tliere are 

 unquestionably two types of schizonts present. The one produces large merozoites with 

 a well-marked nucleus showing a well-marked karyosome, closely resembling the young 

 macrogametocyte described on page 358. The other type of schizont divides into small 

 merozoites which are more numerous than the above, and which have a nucleus with a 

 small karyosome and numerous small granules of chromatin as in the young micro- 

 gametocytes described later. This double schizogony has been described in Adelea ovata. 



SroKOGONY Cycle 

 Microgamete Formation (Plate XIX., ligs. 1-14) 



The microgametocyte is first seen in the cell as a small body about 3-4/i in 

 diameter, with an indefinitely outlined nucleus containing small granules of chromatin and 

 one larger one, the karyosome, generally a little separated from the others, which 

 are arranged in a crescentic manner on one side of it. The karyosome divides first 

 and this is followed by the division of the remainder of the nucleus. Frequently, division 

 is more rapid, the karyosome dividing twice before division of the rest of the nucleus takes 

 place. Concurrently with this the protoplasm of the microgametocyte increases in amount. 

 Division goes rapidly on, the nuclei arranging themselves around the periphery of the 

 microgametocyte until a large body is formed often 30^ in the longest diameter, and 

 the number of nuclei is often so great that the surface becomes involuted to accommodate 

 them all. The size of the adult microgametocyte, and the number of nuclei present in 

 it, vary considerably at the time the final changes begin to take place. The only apparent 

 i-eason for this irregularity seems to be the varying amount of pressure exercised by the 

 surrounding tissue and parasites. 



When division of the nuclei has stopped, the small granules of chromatin in each 

 nucleus condense into a small ovoid body with the karyosome slightly sepai-ated from it at 

 one pole. This arrangement of the karyosome is much better seen in sections stained 

 by Twort's or Giemsa's stain, than in those stained by iron haeinatoxylin (Plate XIX., fig. 13, 

 and Plate XX., fig. 4). These ovoid bodies gradually lengthen out into thin spindle shapes, 

 and arc all arranged round the mass or masses of residual protoplasm. Whether there 

 is one centre or more depends on the frequency of division of the nuclei of the 

 microgametocyte and the subsequent involution of the surface. 



The adult microgamete has a terminal llagellum and a vacuole situated about a third 

 of its length from the one end of the body. The karyosome seems to disappear, 

 but may possibly reappear as the flagellum. I have only seen the vacuole definitely 

 in the tissue lately sent home by Dr. Balfour, and even there it does not appear readily 



