on muscular Motion. 
5 
membrane is in some parts coarse, and in others delicate : the 
heart is always compacted together by a delicate reticular 
membrane, and the external glutaei by a coarser species. 
An example of the origin of muscle is presented in the 
history of the incubated egg, but whether the rudiments of 
the punctum saliens be part of the cicatricula organised by the 
parent, or a structure resulting from the first process of incu- 
bation, may be doubtful : the little evidence to be obtained on 
this point seems in favour of the former opinion ; a regular 
confirmation of which would improve the knowledge of animal 
generation by shewing that it is gemmiferous. There are suf- 
ficient analogies of this kind in nature, if reasoning from 
analogies were proper for the present occasion. 
The punctum saliens, during its first actions, is not encom- 
passed by any fibres discoverable with microscopes, and the 
vascular system is not then evolved, the blood flowing for- 
wards, and backwards, in the same vessels. The commence- 
ment of life in animals of complex structure is, from the 
preceding fact, like the ultimate organization of the simpler 
classes. • 
It is obvious that the muscles of birds are formed out of the 
albumen ovi, the vitellus, and the atmospheric air, acted upon 
by a certain temperature. The albumen of a bird’s egg is 
wholly consumed during incubation, and the vitellus little di- 
minished, proving that the albumen contains the principal 
elementary materials of the animal thus generated ; and it 
follows that the muscular parts, which constitute the greater 
proportion of such animals when hatched, are made out of the 
albumen, a small portion of the vitellus, and certain elements, 
or small quantities of the whole compound of the atmosphere. 
