JuLy 21, 1899.] 
nation of the method by which it enters 
the lacteal. The villus is enclosed exter- 
nally by the epithelial layer, and its center 
is occupied by the lacteal. In the space 
outside of the lacteal and inside of the 
epithelium there is the connective tissue 
(in which the fat is scattered) and muscle 
fibers. These muscle fibers lay along the 
length of the villus. They are attached to 
the connective tissue at the base of the 
villus and inserted in the inside of the 
epithelial row and in the walls of the lac- 
teal. Now, when the muscle contracts it 
will pull upon the connective tissue fibers 
that bind it to the lacteal and to the epithe- 
lium, and these, in their turn, pull the epi- 
thelium inwards and the wall of the lac- 
teal outwards. The force is the same in 
both cases, but the epithelium is far more 
resistant than the wall of the lacteal, and 
the result is that the volume of the vessel 
is increased. This causes a negative pres- 
sure within the lacteal (valves prevent its 
filling up from the large lymphatic vessels) 
and a positive pressure in the stroma be- 
tween it and the epithelium, and in conse- 
quence the peri-cellular fluid, with its fat, 
is forced to enter it. From the lacteal it, 
of course, enters the lymphatic system and 
eventually the blood. 
The other theory gives to the leucocytes 
the primary role in the absorption of fat. 
This holds, in general, that fat, and other 
food as well, is taken from or from between 
the cylinder cells by leucocytes and by them 
earried into the circulatory system. The 
details are held to be as follows: The eat- 
ing of a meal brings about great activities 
on the part of the leucocytes. The number 
of them in the intestinal walls increases 
manyfold. This increase is brought about 
in two ways. ‘There is active cell-division 
on the part of those leucocytes present in 
the nodules and scattered throughout the 
mucosa, and, in addition, there is a migra- 
tion from other parts of the body. The 
SCIENCE. 79 
facts upon which this belief is based are 
the great increase in size of the nodules 
during absorption and the presence of in- 
numerable mitoses in the cells themselves. 
One observer (Schafer) describes the pro- 
cess for the frog as follows: Beneath the 
epithelial row the leucocytes divide, the 
new cell consisting of a nucleus with a 
minute quantity of protoplasm. It moves 
either close up to or between the epithelial 
cells and ingests food. During this process 
it increases enormously in size and event- 
ually carries the load of food back into the 
connective tissue, where it enters a lymph 
capillary. That it is food which the leu- 
cocyte carries back, seems to be proved by 
fat feeding, following which the returning 
leucocytes contain granules that give the 
osmic-acid test. 
These two theories are contradictory, but 
not mutually exclusive, for it is conceivable 
that both processes may take place side by 
side. Leucocytes are known to ingest for- 
eign substances while in the blood, and, al- 
though there are reasons for supposing that 
this phenomenon is of the utmost benefit to 
the organism as a whole, it is not suppos- 
able that leucocytes have been evolved for 
the particular function of disposing of path- 
ogenic bacteria. Similarly, in the intestine, 
the proximity or actual contact of foreign 
substances in the form of fat globules would 
undoubtedly provoke activities on the part 
of the leucocytes. They would ingest such 
particles freely, but rather for their own in- 
dividual benefit than for that of the organ- 
ism as a whole. This would, of course, be 
of benefit to the organism as a whole, since 
the return of the leucocytes to the lym- 
phatic system and their death there would 
increase the amount of food in the lymph, 
but this conception differs very materially 
from that which holds that leucocytes func- 
tion as fat carriers and that without them 
fat could not enter the lymph. There is, 
moreover, direct evidence which bears on 
