EEVIEWS. 
219 
assumes an important aspect. The writer, having shown the resemblance of 
the epithelium of the intestine of the higher animals to the sarcode covering 
the canals of the sponge, proceeds to the conclusion that these tissues are the 
sole agents by which food is digested and absorbed, and that in both cases 
(if w^e have caught his meanmg) the particles of food become embedded in 
the sarcodic substance. After showing the similarity in structure which 
exists between sarcode and epithelium, he proceeds to describe how 
the molecules of food travel into the substance of the epithelium-sarcode, 
and become smaller and smaller as they approach the deeper tissues of the 
animal. 
“ The mucous membranes of the intestines of a mouse, which was drowned 
in warm water to preserve the tissues during examination as nearly as 
possible m a natural condition, when examined by transmitted light with a 
microscopical power of 666 linear, presented the same characteristic appear- 
ances” [as those of sarcode of sponge under like circumstances — Key.] 
“ Some portions of the mucous lining of the intestine abounded more in 
particles than others ; they also varied considerably in size, and were all 
more or less in a state of collapse, and some had the appearance of living and 
fully-distended vesicles. These molecules were not confined to the surface 
of the mucous or sarcodous matter, but were also embedded at various depths 
in its surface. They varied considerably in size and character within a 
small distance. At one place I observed a group of them, each being com- 
paratively of considerable size, while at a little distance there was very rarely 
a large particle to be observed ; and when they appeared to be of more than 
average number and size, they were observed to be at the surface of the 
mucous or sarcodous structure, as if they had not yet been absorbed and 
lessened in size by the process of digestion.” 
If this observation be confirmed, it will throw an entirely new light 
upon the hitherto obscure subject of digestive absorption, and we 
•confess that, a 'priori, there seems every reason why Dr. Bowerbank’s 
doctrine should receive favourable consideration. The accounts of 
the several tissues and organs, and of the functions of nutrition and 
reproduction, are equally instructive and full of original matter, but 
cannot be further referred to for want of space. However, they will 
well repay a careful perusal ; and though they relate to the lower types 
of animal existence, they offer many subjects for contemplation to the 
physiologist, who, by investigating the animal functions in their sunplest form 
and under the smallest number of associated conditions, cannot fail to be 
impressed with the belief that, a knowledge of the operations of life must be 
based upon an impartial examination of phenomena as they present them- 
selves in all members of the animal kingdom. The present volume is ac- 
companied by thirty-seven beautiful lithographic plates illustriitive of 
sponge-anatomy, and we heartily commend it to the notice of our 
readers. 
