Opalina. 219 
slides the endosare spherules were present in their usual abundance 
but were unstained. 
In the Salantidia on both lots of slides there were abundant 
spherules in the endosare which took the safranin well, each 
spherule showing a red peripheral layer and an unstained or faintly 
stained core. 
The natural interpretation of all these microchemical tests and 
digestion experiments seems to be: 1) that the endosare of Opalina 
contains a nutrient substance abundant in freshly taken O. caudata 
and in many individuals of O. dimidiata and in parts of the body 
of many individuals of O. ranaruwm; in starved individuals its pre- 
sence is infrequent. This nutrient material seems to be usually in 
solution in the endoplasma, though even in living animals it may 
form some irregular semi-solid masses. In some cases the endosare 
spherules as well as the endoplasma seem to be permeated by the 
nutrient fluid, but usually they are not so. 2) The nutrient sub- 
stance is not true glycogen, but seems to be related to glycogen. 
The term paraglycogen which Birscunr has suggested seems to be 
appropriate. 3) The endosare spherules are not oil for they do not 
stain with osmic acid or dissolve with alcohol or ether or xylol. 
4) The endosare spherules are not lecithin for they do not dissolve 
when warmed for four hours with a mixture of equal parts of ab- 
solute alcohol and ether. 5) The ectosare spherules for the same 
reasons are neither oil nor lecithin. 6) Probably neither sort of 
spherules contains true glycogen; whether they contain any related 
substance is uncertain. I have failed to get a sugar reaction with 
Frasuina’s solution after diastatic digestion, but this test is not a 
very sensitive one. 7) The spherules of the endoplasma of Nycto- 
therus and Balantidiwm, seem to be composed of paraglycogen. It 
is, of course, natural to suppose that those of Opalina are of a 
somewhat similar nature, but they are not exactly similar chemi- 
cally, as is shown by the difference in their reaction to iodine and 
to Fiscuer’s glycogen stain. 
The whole subject of the nutrient fluids and refractive bodies 
in the cytoplasm of the Protozoa needs more successful study than 
it has yet received. For valuable papers upon the subject see 
Certes (1880), Maupas (1885, 1886), BarrurrH (1885), Birscuur 
(1885 6, 1880—1889 and 1906')), Sronc (1900) and Borr (1907). 
1) In some way I overlooked this valuable paper of Birscu11’s upon the 
paramylon bodies of Huglena, and I have not yet had opportunity to study the 
spherules in Opalina in the light of Birscuii’s work. There is much divergence 
