H. N. RAY                                     185

this is exactly the picture of the nucleus which one gets so often in dry pre-
parations stained with one of the Romanowsky stains. But it must be said
that this holds good only in cases where we are dealing with the typical pear-
shaped organism. In rounded or amoeboid forms a single deeply stained
granule is usually more prominent than others (Plate IV, fig. 2). In
preparations fixed in any of the fixatives mentioned above and stained in
iron-alum-haematoxylin shows only a dark dot at the apex of the parasite and
sometimes a dark thread-like structure can be seen extending from it. The
granule at the broad end which is two to four times as big as one at the apex,
also takes up a deep black stain, but in no case was this structure seen to be
connected with that thread. Dennis [1930] has also called this bigger granule
the nucleus and has shown that it is connected with the smaller one which
he refers to as the blepharoplast by means of a rhizoplast. Round this bigger
granule he has demonstrated the presence of a nuclear membrane—a structure
which unfortunately could neither be seen by Rees [1934] or by the author.
It will, however, be seen later on that the bigger granule is devoid of true chro-
matin and has, therefore, no connection with the nuclear apparatus of the
parasite.

In Feulgen preparations the substance contained in the bigger granule
at the broad pole is completely hydrolysed and appear as a vacuole when
counterstained with light green, while that at the apex gives a definite chro-
matin reaction (Plate IV, fig. 4). The nucleus in such preparations
appears to consist of a deeply stained karyosome usually situated at the ex-
treme narrow end and surrounded by a circle of fine granules. These fine
granules may sometimes take up a linear position keeping the karyosome
either at its apical, central or lower end. The number of these fine granules
varies and are arranged at the periphery of an achromatinic nuclear mem-
brane.

After Feulgen's reaction some smears were stained with iron-alum-
haematoxylin. In these preparations the nucleus presented the same picture
as mentioned above except that the nuclear membrane was more deeply
stained. A very striking feature which was noticed in this preparation was
that the area completely hydrolysed by Feulgen reaction and appeared as a
vacuole, had taken up a deep black stain (Plate IV, fig. 5). Smears fixed
in Carnoy's fluid and stained either with iodine or Best's carmine, however,
revealed the true nature of this granule. With iodine it gave a pale brown
reaction, while with Best's carmine it appeared as a faintly pink area;
suggesting thereby that this area contained certain substance which is allied
to glycogen.

It is now clear, therefore, that the deeply staining granule at the broader
pole of the pyriform body has no relation with its nuclear apparatus, but
instead, is a product of metabolic activity of the parasite. This finding also
explains why this granule does not constantly occur in every individual para-
site at every stage.