1062 



YEKTKBRATED ANIMALS 



Many anatomical parts, when well injected and mounted, become 

 objects of both interest and instruction. This is the case with the 

 villi of the intestine, seen in fig. 793, which presents a transverse 

 section, in which they are seen in situ. A thin section of the toe 

 of a mouse (fig. 794) is another illustration of the effectiveness of 

 this mode of preparation. 



A relation may generally be traced between the disposition of 

 the capillary vessels and the functions they subserve ; but that 

 relation is obviously, so to speak, of a mechanical kind, the arrange- 



FIG. 795. Capillary network 

 around fat-cells. 



FIG. 796. Capillary network of 

 muscle. 



ment of the vessels not in any way determining the function, but 

 merely administering to it, like the arrangement of water or gas 

 pipes in a manufactory. Thus, in fig. 795, we see that the capil- 

 laries of adipose substance are disposed in a network with rounded 

 meshes, so as to distribute the blood among the fat-cells ; whilst in 

 fig. 796 we see the meshes enormously elongated, so as to permit 

 the muscular fibres to lie in them. Again, in fig. 797, we observe 

 the disposition of the capillaries around the orifices of the follicles 



FIG. 797. Distribution of capil- 

 laries in mucous membrane. 



FIG. 798. Distribution of capil- 

 laries in skin of finger. 



of a mucous membrane ; whilst in fig. 798 we see the looped 

 arrangement which exists in the papillary surface of the skin, and 

 which is subservient to the nutrition of the epidermis and to the 

 activity of the sensory nerves. 



In 110 part of the circulating apparatus, however, does the 

 disposition of the capillaries present more points of interest than it 

 does in the respiratory organs. In bony fishes the respiratory surface 



Robin's work, Du Microscope et des Injections ; Prof. H. Frey's treatise, Das Mikro- 

 skop itnd die inikroskopische Technik ; Dr. Beale's How to ^vork with the Micro- 

 scope ; the Handbook to the Physiological Laboratory ; and Rutherford's and 

 Schafer's treatises on Practical Histology. 



