142 E. A. MINCHTN AND K. M. WOODCOCK. 



sometimes tend to ran topfether, or to lie in short streaks. In 

 no case have we observed any signs whatever of a flefinite 

 central body or karyosome in the nucleus. 



In individuals stained very faintly and sharply on the 

 particular Giemsa-stained smear to which allusion has been 

 made several times, the above-described characters of the 

 nucleus can be made out quite well (cf. figs. 5-10). In such 

 cases the picture represents fairly accurately the true con- 

 dition. In other individuals, however, slightly more deeply 

 stained, the nucleus appears more granular and already some- 

 Avhat "blotchy"; this is due to the enlargement of the 

 chromatic grains and to the deposition of the red stain in the 

 nuclear sap, more or less occluding and obliterating the 

 reticulum. This leads on naturally to the appearance generally 

 seen in deeply stained Giemsa smears of a dense mass, staining 

 red or purple, in which bodies and streaks still more darkly 

 coloured can be made out^ representing the chromatic grains. 



We may add that we have been struck by the considerable 

 resemblance between the nucleus of the parasite and that of 

 its host-cell ; this will, indeed, be apparent from many of the 

 figures (fig. 14). 



Turning now to the trophonucleus of a trypanosome, Ave 

 find a remarkable contrast. T. raise being a very large 

 trypanosome and possessing a correspondingly large nucleus 

 is a most advantageous form to study for this purpose, since 

 the various nuclear details — particularly of the karyosome — 

 can be made out more readily than in the ease of a compara- 

 tively small parasite, such as T. lewisi, for example. 



Our description is based upon the appearances yielded 

 after iron-hfematoxj^lin and Twort, for in this case — far more 

 so than when considei'ing the hremogregarine nucleus — it 

 would be difficult, if not impossible, to arrive at what we 

 regard as the correct interpi'etation of the nuclear structure 

 by studying the Giemsa appearance alone. Having obtained 

 a fairly accurate idea of the nuclear constitution from iron- 

 hagmatoxylin and Twort preparations, we can then interpret 

 the widely different picture seen after Giemsa. Miss Robertson 



