358 



COCCIDIOSIS OK TlIK INTKSTINK IS THK (iOAT 



Staining 

 peculiarity of 

 the chromatin 

 of niacro- 

 ganietocyte 



Fertilisation 



witli iron lKi;iiiiito\ylin staining. It was best observed l)y stainiii{{ witli Elirlich's 

 lui'iiiatoxylin and eosin (fixation various). As my drawings were finished before 1 received 

 this last tissue, the vacuole is not shown. 



Macrogainete Formation (Plate XIX., tigs. 15-28) 



The youngest form of the niacrogametocyte observed is considerably larger than that 

 of the niicrogainetocyte, being 5 fi~G fi in its longest diameter, and the protoplasm stains 

 more readily with acid stains than that of the niicrogainetocyte. The nucleus has a 

 marked kuryosome, but except in the earliest stages there is very little other chromatin 

 present. A very interesting peculiarity of the chromatin in the niacrogametocyte is that 

 it seems impossible, in tissue fixed in corrosive sublimate and glacial acetic acid, to stain it 

 with basic dyes, such as the blue in Giemsa's stain and the neutral red in Twort's stain, 

 though it stains readily with iron hsBinatoxylin (Heidenhain). The chromatin in the 

 niicrogainetocyte is readily stained by the basic stain in these two preparations. 



The karyosomu at any early stage divides, and one-half is extruded from the cell 

 nucleus and cell, and is often seen as a cap of chromatin flattened out between tiie parasite 

 and its containing cell, while tlie remaining portion divides again. The one part of this 

 is again extruded or absorbed, while the remainder persists as the karyosome of the 

 adult macrogainete. 



The niacrogametocyte enlarges, and, soon after the second division of the karyosome, 

 granules appear in the protoplasm, at first siuall but eventually growing much larger. 

 These granules retain iron hiematoxylin stain well, though not so markedly as the 

 karyosome. They stain deeply with the acid stain in Giemsa and Twort. 



Enlargement to full size, 26/i-28 /x x 17 ^i-lS ft, goes on without much further change, 

 except that the nucleus becomes enlarged and vesicular with the single marked karyosome 

 remaining. The granules in the protoplasm also become larger and more marked, when 

 nearly adult capsule formation commences. Granules are secreted which stain readily 

 with iron haematoxylin, much less readily with Uelafield or ordinary haematoxylin, and not 

 at all with either the basic or acid stains in Giemsa or Twort. These granules arrange 

 themselves round the periphery of the macrogainete, appear to be extruded and then to 

 flatten out on the outside of the parasite, openings being left between the various plaques 

 thus formed which fuse at first in places, then altogether except for one opening left at 

 one end of the long diameter of the cyst wall to form a micropyle. A cone of attraction 

 appears at one end of the parasite which is directed towards the opening in the cyst. 



Fertilisation apparently takes place at this stage from the change in the character 

 of the nucleus, though I have been unable to find direct proof of the entrance of the 

 niicrogamete. In the apparently unfertilised macrogainete, the nucleus possesses but 

 little chromatin besides the karyosome, whilst, apparently after fertilisation, the whole 

 nucleus becomes a dense mass, staining strongly with iron hajinatoxylin and irregular 

 in outline. At this stage, too, there are seen in the protoplasm numerous small irregular 

 masses staining like chromatin. Are these portions of the karyosome expelled from the 

 nucleus as described by Schaudinn, or are they remains of numerous microgametes which 

 have entered the macrogainete and become degenerate as described by the same observer 

 in Gijcloapiira cari/oli/tica in the mole, which this coccidium seems closely to resemble 

 in its sexual development ? There is no definite evidence. 



As mentioned above, 1 have not been able to follow the matter further, and so have 

 no knowledge of the number of spores or sporozoites formed. All that I have seen in 

 examining the fiEces are a few coccidia in the same stage of development as the most 

 advanced of those in the intestinal mucous membrane. 



