676 



THE MICROSCOPE. 



similar in structure to the perspiratory ducts, being com- 

 posed of thrpo layers derived respectively from the scarf- 

 skin, which lines their interior ; 

 ^he sensitive skin, which is the 

 medium of distribution for the 

 vessels and nerves ; and the 

 'orium, with its fibres, giving 

 'hem strength and support. 

 Like the sudoriferous ducts, they 

 are in some situations spiral ; 



Fig.311. Capillary network and dis-\)\}t this is not a constant fea- 



tribution of papillae over the tongue. , _p ,-\ ,1 



ture ; more irequently they pass 



directly to their destination ; they are also larger, as 

 shown in fig. 312, proceeding from the oil or fat vesicle 



situated at its 

 lower extremity. 

 Oil - glands are 

 freely distributed 

 to some parts, 

 whilst in others 

 they are entirely 

 absent : in a few 

 situations they are 

 worthy of parti- 

 cular notice, as in 

 the eyelids, where 

 they possess great elegance of distribution and form, and 

 open by minute pores along the edges of the lids ; in the 

 ear-passages, where they produce that amber-coloured 

 substance known as the wax of the ears ; and in the scalp, 

 where they resemble small clusters of grapes, and open in 

 pairs into the sheath of the hair, supplying it with a 

 pomade of Nature's own preparing. 



Internal parts of the body. We shall now have under 

 consideration cells of a much higher order than any before 

 referred to ; the cell found floating in the animal fluids is 

 known as the blood-cell, and requires a vascular system of 

 its own for distribution over the whole animal body. 

 The red blood cells, or corpuscles, have a circular form, 

 somewhat flattened ; their size is about l-3,200th of an 

 inch in diameter. It is well known that the blood-cor- 



Fig. 312. Distribution of the tactile nerves at the 

 extremity of the fingers, as seen in a thin perpen- 

 dicular section of the skin. 



