30 H. M. WOODCOCK. 



diffuse nuclear sap. Neither did picro- and para-carmine^ in 

 staining entire adillts, seem sufficiently powerful cliromatic 

 stains to reveal the whole structure. Tliey served to give a 

 general idea of the position, etc., of the nucleus in relation to 

 the cytoplasm, and of the structure of the karyosonie, and 

 that was all. Now, the chroraatiu is by no means all confined 

 to the latter. Whether the parasites have been fixed with 

 sublimate and acetic or with Flemming, hannatoxylia re- 

 veals a distinct, well-marked (linin) reticulum, impregnated 

 with chromatin,^ the latter occurring sometimes as local 

 thickenings of the network, and at other times as numerous, 

 distinct, but small granules and dots. This is shown in 

 figs. 18 and 19, PI. 2, also oti a larger scale in figs. 35 

 and 36, PI. 4. 



The nuclear membrane is generally well marked, and, in 

 perfectly fixed nuclei, of evenly-rounded contour. I have 

 never seen, in any of my preparations, the least sign of a so- 

 called " geflammte Kern." In one or two instances, e.g. 

 fig. 36, the membrane appears irregular and shrunk, but this 

 is entirely due to contraction on fixation. As a rule, it stains 

 deeply, and probably itself contains chromatin; moreover, 

 the reticular threads often start from it. 



The kai-yosome (always single) is more or less vacuolated 

 in structure, and, certainly in some cases, is slung in position 

 by very distinct threads of the reticulum (figs. 19 and 35) 

 which appeared to end in it. In other cases this is not so 

 marked, and the karyosome seems more suspended in the 

 network — as if, to use a borrowed expression, " it was a 

 football lodged in the branches of a tree." In all the 

 trophozoites, however small, which I have examined, the 

 nucleus has invariably a karyosome of some sort. The size 

 and number of the vacuoles it contains is very variable, and 

 to a certain extent dependent upon the age of the nucleus ; 



' Also in tlie case of Laiikesteria ascidiae, Siedlecki (loc. cit.) has 

 pointed out that the nucleus has a distinct clnoniatic reticulum, in wliich are 

 suspended as well some comparatively larg'e grains of chromatin (see his figs. 

 2 and 3). 



