148 E. A. MINCHIN AND 11. M. WOODCOCK. 



ance is quite easily capable of explanation when the known 

 tendency of the Romanowsky stain to be deposited in excess 

 around anything of a chromatic nature is borne in mind. We 

 may suppose that in such cases there is a cei-tain amount of 

 chromatin distributed in the nuclear sap or karyolyinph (in 

 addition to that associated with the karyosome); this is most 

 probably in the form of very fine granules, which are of 

 course magnified by the stain to many times their real size. 

 Hence the effect is produced of a granular mass, such as has 

 been so often described. By this means the clear central 

 area, indicating the position of the karyosomatic body, is 

 generally occluded completely and indistinguishable. 



We have now to consider, briefly, the hasmogregarine- 

 nucleus. Here, too, there can be no question but that the 

 true nuclear structure is better revealed by stains like iron- 

 heematoxylin and Twort than by the Romanowsky method of 

 staining. Nearly all the illustrations of haemogregarines 

 which we have seen are from parasites obviously stained by 

 the latter method. Prowazek, it may be mentioned, in his 

 paper on H. platydactyli (16), has three figures which 

 were drawn from preparations stained by Grenacher's haema- 

 toxylin, and these also give indications of the same type of 

 structure — an irregular reticulum carrying chromatin-grains 

 and masses of various sizes — which we have found in H. 

 rovignensis. The nuclei in these figures of Prowazek' s 

 differ very greatly from those he has drawn from Romanowsky 

 preparations; many of the latter, we are convinced, do not 

 give at all an accurate idea of the nuclear constitution. 



Of all the other figures of h^emogregarine-nuclei at which 

 we have looked, those of Borner, in his account some years 

 ago (4) of reptilian hgemogregarines, seem to convey most 

 approximately the true idea of the nucleus. From his 

 " Tafelerklarung" we gather they were drawn from 

 Romanowsky pi'eparations ; but for this intimation we should 

 have regarded them as from preparations stained by some 

 hEematoxylin method, both from the appearance of the nuclei 

 and from the manner in which the figures are coloured. We 



