1880. ] Zoology. 527 
doctrine of development, shows that it by no means involves, but 
rather disallows, the existence of continued transformation of the 
not-living into the living, unless passed through, so to speak, the 
alembic of life. To suppose any hesitancy on the part of any 
truly scientific mind in receiving the evidences of abiogenesis if 
they could be satisfactorily shown, is too ridiculous for repetition. 
It would be more than weakness, however, to receive as evidence 
what is not such. Let ¢rwéh come from whence it may, and point 
never so grimly to where it may, he would be recreant to science, 
who would for one moment hesitate to receive it. But not less 
false is it to the foundation principles of true science, to accept 
as true, what must constitute the roots of vast generalizations, 
<a on evidence which no future scrutiny or analysis can 
shake.” 
THEORY OF Birp Micrations.—I am not aware of the appli- 
cability of the following to all parts of the country, but am con- 
vinced that I have the facts in regard to the migrations of birds 
in Illinois. For four seasons I have carefully noted the bird arri- 
vals in Illinois, the results of which have been published in the 
Chicago 7ridune as annual reports, 
In each instance noted, the first four species to arrive and which 
all arrived together, were the robin, meadow lark, grosfinch and 
bluebird. In each instance these species came with a terrific gale 
of hot wind from the south, which lasted some two or three days 
and nights, The thermometer on each occasion stood at 70° F. 
Now to my mind the time of migration is set by the continu- 
ance of this excessive heat and current of air. 
I have two proofs of this. In 1878 there was an open winter 
and they did not arrive until late in the spring, though the ther- 
mometer stood generally at 30° and 40° each day. It was not 
until the several days of hot air with a thermometer at some 70° 
that they arrived. 
Again, this season a hot air current came, lasting one ay and 
part of a night, with the mercury at 70°, only a few robins came, 
and the migrations were not general even with this species ; the 
other three species wisely staid away, waiting for the usual three 
days of hot air. I am confirmed in this opinion in the fact that 
in the spring of 1879 I wrote out my account of the bird arrivals 
for this region (Evanston, Ill.), and five days later visited Northern 
New York; there was four feet of snow at Oswego, and of course 
hota summer bird had made an appearance. It was about the 
” first of April when the three days’ current of hot air reached 
Oswego county, and then the birds arrived. 
Migrations, then, depend, as to time, on a continuous current of 
= air and high temperature, extending at least through sixty 
ours 
As to the route of the migrations, I coincide with the opinion 
