320 
WONDERS OF THE MICROSCOPE. 
Confirmations of this view of the structure of muscular 
fibre have recently been received from various quarters, one 
of the most important being the observations made by Dr. 
Lister, who sums up the results of his investigations as follows : 
u In the arteries of the frog, and in the intestines of the pig, 
the involuntary muscular tissue is composed of slightly flat¬ 
tened elongated elements, with tapering extremities, each pro¬ 
vided at its central end and thickest part with a single 
cylindrical nucleus imbedded in its substance. It further 
appears that in the pig’s intestine the muscular elements are 
on the one hand capable of an extraordinary degree of ex¬ 
tension, and on the other hand are endowed with a marvel¬ 
lous faculty of contraction, by which they may be reduced 
from the condition of very long fibres to that of almost glo¬ 
bular masses.” 
The discovery of these “ contractile or muscular fibre-cells,” 
as Kblliker termed them, is one of the most important and 
beautiful ever made in anatomy. 
In passing, we will now notice the characteristics which dis¬ 
tinguish the animal from the plant. It is when we examine 
the nutrition of the vegetable and animal kingdom that we 
find characters and properties peculiar to each; even in the 
lowest and simplest forms of both these are most distinctly 
delineated. For the Protophytes, like the perfect plants, draw 
their nutriment from the inorganic compounds—water, 
carbonic acid, and ammonia ; by decomposing carbonic acid 
they give off oxygen, and by this process form for them¬ 
selves the starch, the cellulose, and the albumen, which is 
applied to the augmentation of their own substances. On 
the other hand, even the humblest Protozoa can only exist (so 
far as we can see) upon materials previously elaborated by 
other organisms of equal simplicity; these they receive 
bodily into their interior—though mouth, stomach, intestines, 
and anus, all have to be quickly passed every time the 
animal feeds, yet the digestion which the alimentary par¬ 
ticles undergo is not less complete than in the most elaborate 
digestive apparatus. Thus, notwithstanding the remark¬ 
able analogy which these two orders of beings exhibit, we 
cannot see that any difficulty need be experienced in sepa¬ 
rating them, when we are acquainted with their modes of 
nutrition. 
The microscope, in conjunction with chemistry which, if 
it cannot imitate, is at least beginning to trace accurately the 
changes undergone by the elements contained in a living 
cell, and is hastening the time when physiology shall pass from 
the speculative to the certain sciences, and medicine no longer 
remain a conjectural art. 
