246 A. B. MACALLUM. 
he took to be a nucleus, but this body, when hardened with 
corrosive sublimate, stains with eosin but not with hema- 
toxylin, while after fixation with Flemming’s fluid it appears 
to have no particular affinity for any dye. On the other 
hand, in S. Ludwigii, as it usually develops in the sap of the 
iron-wood tree (Ostrya virginica), there is in the great 
majority of cells a corpuscle which corresponds with the 
“nucleus” of Méller. This structure is round, homogeneous, 
and in diameter sometimes more, sometimes less, than half 
the length of the shorter axis of the cell, in the centre of 
which it is usually placed, and after being hardened with 
corrosive sublimate it exhibits a special affinity for eosin, 
but none for hematoxylin, while it acts like the cytoplasm 
towards safranin. In preparations made with Flemming’s 
fluid the results were practically the same, and therefore not 
indicating on the part of the body in question the possession 
of a substance in all points like chromatin. 
A substance like chromatin appears to be distributed 
through the cytoplasm. In S. cerevisiz, after being hard- 
ened with corrosive sublimate, the cytoplasm takes, when 
treated with hematoxylin (Delafield’s and Ehrlich’s), a blue- 
violet tinge. With favourable illumination and apochromatic 
objectives, the stain is found to be localised in the trabeculee 
of the cytoplasmic network, and, where the vesicular character 
of the cytoplasm appears pronounced, all the cytoplasm, except 
the contents of the vesicles, is coloured. In some of the cells 
granules were observed with a stain slightly deeper than that 
of the cytoplasm, and similar elements were found in cells 
hardened with Flemming’s fluid and stained with safranin. 
These, possibly, are those described by Raum. In 8. Ludwigii 
the cell is usually very much larger, and the structure and 
staining reactions are, therefore, much more distinct. In this 
form, when hardened with corrosive sublimate and stained 
with hematoxylin, the vesicular structure of the cytoplasm 
comes out quite markedly through its blue-violet stain, which 
also is found now and then to characterise prominently gran- 
ules in the cytoplasm between the vesicles. The granules of 
