hung, one after another, on the wall of his study, but
she was able to follow them only in a general sense. The technical
details escaped her.

Nuwell seemed to have a better grasp of the subject. He nodded his dark,
curly head frequently, and occasionally asked a question or two.

"Surgery is performed with a concentrated electron stream on the cells
of the early embryo," said Goat. "I call it surgery, but actually it is
an alteration of the structure of certain specific genes which govern
the characteristics I am attempting to change. Such changes would, of
course, then be transmitted on down to any progeny.

"The earlier the embryo is caught, the easier and surer the surgery,
because when it has divided into too many cells the very task of dealing
with each one separately makes the time requirement prohibitive, besides
multiplying the chance for error. The Martians have a method of altering
the physical structure and genetic composition of a full-grown adult,
but this is far beyond the stage I've reached."

"The Martians?" repeated Nuwell in astonishment. "You mean the Martian
natives? They're nothing but degenerated animals!"

"You're wrong," replied Goat. "I know that's the general opinion, but I
had considerable contact with them a good many years ago. Perhaps most
of them are little more than strange animals. No one really knows. They
live simple, animal-like lives, holed up in desert caves, and they're
rarely communicative in any way. But I know from my own experience that
some of them, at least, are still familiar with that ancient science
that they must have possessed when Earth was in an earlier stage of life
than the human."

"This ... child ... that brought us the wine is one of the products of
your experiments?" asked Nuwell.

"Yes. Petway's pretty representative of the children, I'm afraid. I've
been trying to determine what went wrong. It could be an inaccuracy in
dealing with the genetic structure itself, or a failure to follow
exactly the same pattern of change in moving from one cell to another in
the embryo. If I could only catch one at the single cell stage!

"None of the children has turned out as well as my first two
experiments, Brute and Adam. Both of them were born about twenty-five
years ago--terrestrial years, that is--and developed into normal, even
superior physical specimens. Unfortunately, their mental development was
retarded. Adam was the brighter of the two, and Brute killed hi