704 
ZOOLOGY: CHEPLIN AND RETTGER Proc, N. A. S. 
regarded as equations in t have a unique common solution, <^ may be 
arbitrarily taken and d = t<p. The equations of / are — Ky = Sz — \w = 
0 and the cubic is x = a\ y = a", z = a, w = 1; or finally the involu- 
tion is (7^ — -\- n{S(j — X) a single one determined by each value 
of m. 
Putting X = X — Ky, Y = x — \y, Z = Sz — \w, W = Sz — kw 
the planes X = 0, Y = 0, Z = 0, = 0 are the faces of the tetrahedron 
whose edges are a, c, I, V . The collineations {X' = piX, Y' = p^Y, Z' = 
PiZ, = p^) leave invariant the lines ahcdlV evidently but trans- 
form any cubic tangent to ahcd into an infinity of others. 
The coincidence of the equation between m and n with the modular 
equation leads to this geometrical theorem. If four planes of a pencil 
of axis / touch a cubic and the tangents meet I in ABCD and if the planes 
meet the cubic in simple intersections A'B'C'D' then [A'B'C'D'} = 
[ABCD]. 
STUDIES ON THE TRANSFORMATION OF THE INTESTINAL 
FLORA, WITH SPECIAL REFERENCE TO THE IM- 
PLANTATION OF BACILLUS ACIDOPHILUS, 11. 
FEEDING EXPERIMENTS ON MAN 
By Harry A. Che^pun and Lko F. Rettgkr 
BacterioIvOgicai. Laboratory, Yai^e University 
Communicated by L. B. Mendel, October 20, 1920 
In a recent communication in these Proceedings 6, 1920, pp. 423-426 
the results of feeding experiments with albino rats were presented. Simi- 
lar attempts to implant Bacillus acidophilus in man have led to the fol- 
lowing conclusions. 
Thorough implantation may be effected by the daily administration 
of 300-400 grams of lactose, 300 cubic centimeters of a whey broth cul- 
ture of B. acidophilus (McFarland nephelometer turbidity scale of 5), 
or by a combination of 150 grams of lactose and 150 cc. of the whey broth 
culture. Complete transformation of bacterial types may be brought 
about also by the daily use of 500-1000 cc. of acidophilus milk culture. 
The same results are obtained with dextrin as with lactose, but dex- 
trose, sucrose and maltose exert no flora-transforming influence. 
The time required for changing the flora varies with the nature and the 
amounts of the material administered. The most rapid implantation 
was obtained with the Bacillus adophilus milk. In two of the subjects 
500 cc. of the milk brought about marked alteration within two to three 
days. Some of the subjects that were but slightly affected by 500 cc. 
of the milk culture showed very pronounced transformation when 100 
grams of lactose were added daily to this amount. 
No change could be detected in the hydrogen ion concentration of the 
