HEREDITY IN ANIMALS. 
229 
them of this habit. In 1790 a lamb was born on Mr. 
Seth Wright’s farm which had a long body and short 
bowed legs; doubtless it was a “ sport.” It was soon 
noticed that this lamb could not follow the others 
over the fences, and the owner thought it would be a 
good thing if all his sheep were like it. Accordingly 
he selected this one to breed from. Though some of 
its offspring were like ordinary sheep, a few of them 
inherited its peculiarities—a long body and short 
bowed legs. Thus originated the Ancon breed of 
sheep. 
In the year 1770, in a herd of horned cattle in 
Paraguay was born a ‘‘ sport” which developed into a 
hornless bull. He was used to breed from, and in 
this way was started a hornless breed of cattle. 
By what principle are traits transmitted ? Is there 
any law of heredity ? If so, what is the law ? These 
questions have engaged the attention of evolutionists 
for more than a quarter of a century. In fact, the 
law of heredity is the present-day problem. In order 
to get at it, we must consider the cell, which is the 
basis of all physical being. It is there that life ulti¬ 
mately resides. 
We have already learned that the lowest living 
forms, both animal and vegetable, consist of a single 
living cell, and the most important part of that cell 
is its central portion, called the nucleus. Its structure 
is very complex, and thus far has defied all chemical 
analysis. The microscope reveals to us small threads 
in the nucleus. What have these threads to do with 
the transmission of parental characteristics ? 
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