ning bloody scybala, in diarrheal stools, or rarely even in well- 
formed stools. There are several varieties of this « small généra¬ 
tion ». As seen in stools, they are frequently, though not always 
refractile. When refractile, they stain very slowly intravitam with 
Gentian violet, and hâve no doubt often been mistaken for 
E. coli. When stained by the method mentioned above, one is 
struck by two features, which characterize the smaller senile, or 
precyst génération. First, the presence of more or less large 
blocks of crystalloidal substance (Chatton (i) ) in the cytoplasm. 
Second, the very prominent and densely stained karyosome. This 
génération of trophozoites is the one that preceeds encystment. It 
is also, I believe, the génération described so carefully by Elmas- 
sian as E. minuta (2) and the génération described by others as 
E. tetragena (3). 
Between this génération and that of the large trophozoite, 
there are varieties so far as the amount and shape of chromidia 
and staining characters -of the karyosome are concerned. 
In some of these cases of entamœbic colitis, associated with the 
small or precyst génération, are small cysts containing one, two, 
or four nuclei, and blocks of chromidia. Later, when the colitis 
lias apparently entirely disappeared and the stools hâve becorne 
more or less formed without a trace of mucus, it may be possi¬ 
ble to find few or many tetragena cysts, thus completing the life 
cycle of E. tetragena in the intestinal tract of man ; and it may be 
conceived that of the three phases mentioned : (a) the dysenterie 
trophozoite ; (b) the precyst trophozoite and (c) the cyst. (a) re- 
presents something analogous to adolescence and (b) to maturity 
or senility. 
It can be shown that these terms represent corresponding infec- 
ting powers of the trophozoites in any given case of entamoebic 
colitis. For, if kittens be inoculated rectally with material Tom 
an adolescent or histolytica-like strain, the strain may be carried 
on upon the death of the preceding kitten for four, five, or six 
transfers, the strain thus taking about one month for its sejourn 
in the colon of the kitten, but if, on the other hand, a chromidia 
containing senile « tetragena »-like strain be injeoted rectally 
(1) Chatton, Bull, de la Soc. de Path. Exot t, V, 180, 1912. 
(2) Elmassian, Centralbl. f. Bakt., Parasitenk u. Infek., I, Orig., t. LII, 
335 - 1909- 
(3) Craig, Jour, of Med. Research , XXVI, 1, Apr. 1912. 
