1892.] The Difficulties in the Heredity Theory. 567 
Notre.—Bearing upon the experimental evidence for the 
hereditary transmission of multilations, I have recently 
received, through Dr. Charles E. Lockwood, of New York, a 
letter,’ in regard to some experiments upon mice, which were 
continued over more generations than those of Weismann, 
and with affirmative results: j 
“T selected a pair of white mice on account of their rapid 
_ breeding. I bred them in and in for ninety six generations, 
as they breed every thirty days, and when they are thirty days 
old they are able to reproduce themselves. I destroyed all 
sickly and defective ones by breeding only the fittest. I bred 
all disease out of them, and had a pure-blooded animal, larger 
and finer every way than the original pair. In breeding 
their tails off, I selected a pair and put them in a cage by 
themselves, and when they had young I took the young and 
clipped their tails off. When old enough to breed I selected 
a pair from the young and bred them together, and when 
they had young I clipped their tails. I continued this breed- 
ing in and in, clipping each generation, and selecting a pair 
of the last young each time, in seven generations. Some of 
the young came without tails until I got a perfect breed of 
tailless mice. I then took one with a tail and one without a 
tail and bred them together, and by changing the sexes each 
time—a male without a tail, a female with a tail, and next a 
female without a tail, and a male with a tail—I was finally 
rewarded with all-tail mice.” 
There is such general scepticism now in regard to the 
inheritance of mutilations that it will be necessary to repeat 
such experiments as these in some well-known physiological 
laboratory. As told above, they seem to be trustworthy, but 
facts which go against a theory must be doubly attested. 
1From A. J. S. Shiddell, Lexington, Ky. 
