226 THE AMERICAN MONTHLY [December, 
Slightly saline water was the only medium employed, and it is possible 
that with some other medium, such as serum or the white of an egg, their ex- 
istence might have been considerably prolonged. 
Unfortunately, however, the supply of ¢evedo suddenly fell short, and, no 
more being obtainable, the observations were brought to a close. 
As far the author is aware, these parasites have not heretofore been noticed, 
or at the most, but little is known of them. It is possible that further ex- 
amination in this direction may reveal the existence of still other forms than 
those noted here. or of forms intermediate between some of these. 
It remains also for future observation to determine the life history, habits, 
and detailed structure of these creatures. 
It was the author’s intention to repeat these observations and make this 
series of parasites the subject of more prolonged examination. The oppor- 
tunity for such study, however, being relegated, seemingly, to the distant future, 
these imperfect results of the first observations are given as a hint where a 
comparatively little worked field of examination may be found. 
The crystallography of butter and other fats.—IYV. 
By Dr. THOMAS TAYLOR, 
U. S. AGRICULTURAL DEPARTMENT, WASHINGTON, D. C. 
EXPLANATION OF PLATE V. 
Crystalline Formations of Oleo and Oleomargarine. 
J Ss 
Fig. 1. Boiled oleo by plain light, exhibiting spines.  I4o. 
Fig. 3. Boiled oleo by polarized light, showing a cross. 140. 
Figs. 2, 4, 5, 6, 9, 11, 12, 13, 14, and 15. General appearance of oleomar- 
garine as sold in the market. 75 to IIo. 
Fig. 7. Armour’s oleomargarine boiled and cooled. 140. 
Fig. ro. A specimen of oleomargarine composed mostly of stearin and cot- 
ton-seed oil.  X IIO. 
Fig. 8. Boiled butterine (Armour’s make), showing the oleo crystals. 
I10. 
The above crystals were all photographed by polarized light, except in the 
case of fig. 1, which was by plain light. 
EXPLANATION OF PLATE VI. 
Figs. 1 and 3. Respectively primary and secondary crystals of loon fat. 
KOE 
Figs. 2 and 8. Primary and secondary crystals of musk-rat fat. The primary 
(No. 2) are always very small, measuring about three-one-thousandths of an 
inch in diameter. 
Fig. 4. Crystals of oleo. X 140. (Extract of beef-fat). 
Fig. 5. Crystals of common lard by plain light. x 4oo. 
Fig. 6. Secondary crystals of butter.. X I10. 
Fig. 9g. Crystals of deer-fat. X 140. 
Fig. 10. Lard by plain light. x 140. 
Fig. 11. Crystals of the solid fat of cotton-seed oil. 110. 
4 
5 
6 
Fig. 47. Crystal of beef-fat. >< 140. 
9 
IO 
II 
Fig. 12. Neutral lard crystals, immature. 140. 
