SOME OBSERVATIONS ON A NEW GREGARINE. 271 



formation of the first two daughter-nuclei. — 

 Although the material which I was able to collect was 

 very limited, I was fortunate in obtaining one leech very 

 heavily infected. In the intestine of this animal 1 found 

 numerous cysts, and also an enormous number of adult 

 gregarines mostly fixed to the gut-wall. A study of these 

 sections has revealed several phases of the first division of 

 the nucleus, though to elaborate all the stages is impossible 

 without further examples, which I hope shortly to procure. 

 In order, therefore, to make the most of this limited material, 

 I employed first hasmatoxylin (Delafield's) and eosin, and 

 then after decolorisation with acid alcohol, re-stained by 

 Heidenhain's method. This latter method revealed numerous 

 important facts quite indiscernible with the original staining. 

 My thanks are due to Dr. Pembrey, of Guy's Hospital, who 

 very kindly provided me with all the necessary apparatus for 

 staining. 



For some time at any rate after a definite cyst-wall has 

 formed^ the nuclei of the encysted gregarines remain appa- 

 rently unaltered. Then the chromatin masses begin to frag- 

 ment, with the result that chromidia are formed within the 

 limits of the nuclear membrane. Simultaneously, this mem- 

 brane becomes increasingly thin, and the karyO«ome throws 

 out masses of substance from its interior, becoming in con- 

 sequence markedly reduced in size. These masses are more 

 or less spherical and of distinct outline; they stain very 

 deeply, showing black with iron-hasmatoxylin. Their number 

 and size vary greatly (figs. 9-14). At times one large mass 

 is present, almost equal in size to the original karyosome; at 

 others, numbers of small masses are seen. The actual process 

 of extrusion of one of these masses is shown in fig. 36. After 

 their extrusion, the main karyosome- relic shows a blue colour 

 with h^ematoxylin and eosin, as contrasted with the more 

 purple hue shown by the intact karyosome and the chromatin 

 masses of the trophozoite nucleus. The extruded masses on 

 the other hand behave throughout, as regards stains, like 

 the chromatin masses. After the frnsrmentation of the 



