44 
LIFE, IN ITS LOWER FORMS. 
Pliny alludes to tlie Sponge as one of the articles used 
by painters of his day : it has been conjectured from this 
that water-colours were employed in ancient art, and the 
Sponge probably performed a similar office to that which 
it holds in the hands of a modern artist — washing out 
lights, &c. 
In modern surgery, the use of the Sponge is great. The 
flowing blood in operations is absorbed by it ; acrid dis- 
charges from wounds and ulcers are thus imbibed ; and 
dangerous hemorrhages are checked and sometimes 
arrested by its application. The sponge-tent, formerly 
much used for dilating sinuses and small openings, was 
made by dipping the sponge into molted wax, and then 
compressing it until it became cool, between iron plates.* 
The quality of hilarity in which the value of Sponge 
chiefly consists, is owing to the multitude of minute 
channels with which its whole substance is perforated, and 
is dependent ou the law of capillary attraction. By this 
law fluids ascend, in tubes of small diameter, to a height 
which increases in proportion to their tenuity, as any one 
may observe who will plunge the end of a fine glass tube 
into water. It is not requisite that the tubular form 
should be perfect or uninterrupted ; the interspace 
between two closely approximated fibres will serve as a 
capillary tube ; and thus the sponge-fibres present a series 
of canals, through which any fluid, with which a portion 
of the surface is in contact, will continue to flow until the 
whole are filled. 
A very different process is this spontaneous imbibition 
of water by capillary attraction from that already de- 
* Pereira, Mat. Med. § 1814. 
