144 E. A. MINCHIN AND H. M. WOODCOCK. 



at these points after Twort, however, and so do not feel at all 

 certain that they are chromatin. 



A correct interpretation of the characteristic central body 

 in the nucleus is best gained from Twort films. Iron-ha?ma- 

 toxylin films must be very well extracted, and then the same 

 or a similar condition is revealed. But in those iron-ha3ma- 

 toxylin smears where the whole karyosomatic mass is stained 

 almost uniformly black (as in figs. 53 and 56 for example), it 

 is safe to say that an excess of stain still prevents the details 

 from being apparent. The true structure appears to be as 

 follows : In the centre is a fairly large, clear region, oval or 

 rounded, which is stained grey in ii-on-haematoxylin films and 

 a pale green (distinctly paler than the rays) in Twort prepara- 

 tions. This is the basis or ground-work of the karyosome and 

 is probably of a plastin-like nature. The chromatin is located 

 at the surface, or at any rate in the peripheral region of this 

 plastinoid basis. In the smaller nuclei the chromatin is mostly 

 in the form of granules or small masses of varying number 

 (usually three to five) and size, and more or less separate from 

 each other (figs. 55, 57a, 68a and h) ; but in the large nuclei 

 we frequently find the chromatin forming a complete zone or 

 ring around the paler area, with thickenings or bulgings here 

 and there (figs. 57, / and g, 68, c, d) corresponding to the 

 small masses in the other case. 



One important detail remains to be mentioned, namely, the 

 presence of a small, distinct granule in the centre of the 

 plastinoid area, which is probably of constant occurrence. It 

 is readily made out in Twort preparations (cf. fig. 67, 68, a-f) ; 

 sometimes it is green in colour, but in other cases the colour 

 appears to be a mixture of both the red and the green ; it is, 

 however, never of the same sharp red colour that the chromatic 

 masses are stained. This granule can be distinguished also in 

 the individuals on iron-liEematoxyliu smears, but not so 



easily. 



Comparing, now, the appearance of the nucleus in Giemsa 

 smears, a condition is generally found which at first sight 

 seems to be diametrically opposite to that shown by iron- 



