‘the Physiology of the Egg. S09 
‘their eyes.” If any further testimony be necessary to show that 
‘the augmentation of muscular energy is the result of a nice | 
combination of oxygen with the animal organs, many interesting 
facts might be adduced in confirmation of its truth. We gene- 
rally find the strength of an animal proportionate to the extent . 
of its chest: hence an attention to the *animosum pectus" has 
'been attended with the improvement of our breed of cattle; and 
it is in consequence of a great extent of pneumatic receptacle 
that birds are enabled to bear the prodigious muscular exertion 
offlight. Is it not probable, too, that the repeated suspirations 
of the fatigued are instinctive exertions to procure a greater 
proportion of oxygen, by which their muscular energy may be 
revived? Imust not quit the subject of this follicle, without no- 
icing a very curious fact well known to every one employed in the 
concerns of a farm-yard,—that, if the obtuse extremity of an egg 
be perforated with the point of the smallest needle, (a stratagem 
which malice not unfrequently suggests,) its generating process 
is arrested, and it perishes like the subventaneous egg. Hence 
Sir Busick Harwood was led to suspect that the elastic fluid 
contained iu the air-bag was oxygen, and I was induced to 
examine its nature. Can this curious problem be solved, by 
supposing that the constant ingress of fresh air is too highly ex- 
citing? A parallel example may be adduced from the vegetable 
—." kingdom in support of such an opinion. The young and tender 
. plant, before it puts forth its roots, is often destroyed by having 
too free a communication with the atmosphere, by which its 
powers are exhausted: it is to obviate such an effect, that the 
horticulturist, taught only by experience, covers it with a glass, 
by which he limits the extent. of its atmosphere, and. conse- 
quently decreases its respiration, transpiration, and the inordinate 
actions which would prove fatal to it. Id. vedi mini 
. I VOL X. 2s 
I shall 
