HEALING OF OPEN WOUNDS. 
327 
material is rapidly developed into cells, amongst which blood¬ 
vessels speedily extend themselves. The formation of new 
blood-vessels, in this and other cases, seems to commence in 
the giving-way of the walls of some of the previously-existing 
capillary loops, at particular spots, and in the escape of blood 
corpuscles in rows or files into the soft substance that sur¬ 
rounds them; thus channels or passages are excavated, which 
come into connexion with each other; and these channels, 
after a time, acquire proper walls, and become continuous 
with the vessels from which they originated,—to be in their 
turn the originators of a new series. The vitality of this new 
“granulation-tissue,” however, is very low; and the part ex¬ 
posed to the air passes into the condition of pus (the yellow 
creamy fluid discharged from an open wound), which contains 
the same materials in a decomposing state. Thus there is a 
constant waste of organizable substance, the amount of which, 
in the case of an extensive wound, becomes a serious drain 
upon the system; at the same time, there is a much greater 
irritative disturbance both in the part itself and in the system 
generally; and the new tissue that is formed is of such low 
vitality that it subsequently wastes away, so as by its disap¬ 
pearance to leave a contracted cicatrix or scar.—The difference 
between the two modes of reparation now described is often 
one of life and death, especially in the case of large burns of 
the body in children. 
CHAPTEE IX. 
ON THE EVOLUTION OP LIGHT, HEAT, AND ELECTRICITY BY ANIMALS. 
Animal Luminousness 
394. A large proportion of the lower classes of aquatic 
Animals possess, in a greater or less degree, the power of 
emitting light. The phosphorescence of the sea, which has 
been observed in every zone, but more remarkably between 
the tropics, is due to this cause. When a vessel ploughs the 
ocean during the night, the waves—especially those in her 
wake, or those which have beaten against her sides—exhibit 
a diffused lustre, interspersed here and there by stars or 
ribands of more intense brilliancy. The uniform diffused 
