(The parallel of
curdling milk, which we spoke of before, is no longer in point here,
for what is formed by the heat of the semen is not only of a certain
quantity but also of a certain quality, whereas with fig-juice and
rennet quantity alone is concerned.) This then is just the reason why
in such animals the embryos formed are numerous and do not all unite
into one whole; it is because an embryo is not formed out of any
quantity you please, but whether there is too much or too little, in
either case there will be no result, for there is a limit set alike to
the power of the heat which acts on the material and to the material
so acted upon.
On the same principle many embryos are not formed, though the
secretion is much, in the large animals which produce only one young
one, for in them also both the material and that which works upon it
are of a certain quantity. So then they do not secrete such material
in too great quantity for the reason previously stated, and what
they do secrete is naturally just enough for one embryo alone to be
formed from it. If ever too much is secreted, then twins are born.
Hence such cases seem to be more portentous, because they are contrary
to the general and customary rule.
Man belongs to all three classes, for he produces one only and
sometimes many or few, though naturally he almost always produces one.
Because of the moisture and heat of his body he may produce many [for
semen is naturally fluid and hot], but because of his size he
produces few or one.
Pages:
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203