344 THE MICROSCOPE. 



structure, is termed Physiology, or Biology ;* and that part of it more 

 particularly relating to the minute structure of the organs of animals 

 has been termed Histology.^ It is generally divided into animal and 



DESCRIPTION OF PLATE XII. ANIMAL STRUCTURES. 



No. 1. a, Simple isolated cells containing reproductive granules ; b, mucous mem- 

 brane of stomach, showing cells, with the open mouths of tubes at the bottom of each, 

 magnified 50 diameters. 



No. 2. a, Diagram of a portion of the involuted mucous membrane, showing the 

 continuation of its elements in the follicles and villi, with a nerve entering its sub- 

 mucous tissue. The upper surface of one villus is seen covered with cylindrical epi- 

 thelium ; the other is denuded, and with the dark line of basement membrane only 

 running around it. b, epithelium scales, separated and magnified 200 diameters ; in 

 the centre of each is a nucleus, with a smaller spot in its interior, called the nucleolus. 

 c, pavement epithelium scales, from the mucous membrane of the bronchial or air- 

 tubes of the lung, showing nuclei, with double nucleoli in some, d represents another 

 form of epithelium, termed the vibratile or ciliated ; the nuclei are visible, with cilia 

 at their upper or free surfaces, magnified 250 diameters. 



No. 3. a, is one of the tubular follicles from a pig's stomach, cut obliquely to dis- 

 play the upper part of its cavity, and the cylindrical epithelium forming its walls, with 

 a few of them detached, to show their true form ; and at the lower part, the nucle- 

 ated extremities of the cylinders of epithelium are seen. No. 3. b shows a section of 

 the lymphatics, and capillary blood-vessels, distributed beneath the mucous surfaces ; 

 the lymphatics take their origin from the radiated cells. 



No. 4. Cells of adipose tissue, or fat, magnified 100 diameters. 



No. 5. A single fat-cell separated, and magnified 250 diameters. 



No. 6. A capillary of blood-vessels distributed in the fat-tissue. 



No. 7. Section^ of the tendo-Achillis as it joins the cartilage, showing the stellate 

 cells of tendon gradually coalescing to form the round or oval cells of the cartilage. 



No. 8. A vertical section of cartilage, with clusters of cells arranged in columns 

 previous to their conversion into bone, which is seen condensed at the upper surface. 

 The greater opacity of this portion is owing to the increase of osseous fibres, the 

 opacity of the cell-contents, and the multiplication of the oil-globules ; the dark inter- 

 cellular spaces become filled up with vessels. 



No. 9. A small transverse section of the same, showing the gradual change of the 

 cartilage cells at a into the true bone-cells termed lacunce, at b } with their character- 

 istic canaliculi. 



No. 10 is a stellate nerve corpuscle, with tubular processes issuing from them : at a 

 it is filled with corpuscles containing black pigment, above which is a corpuscle in the 

 nucleus of which is seen nucleoli ; at & is a corpuscle enclosed within its sheath, and 

 filled with granular matter : this is taken from the root of a spinal nerve. 



No. 11 shows the continuity of muscle, the upper portion, with connective tissue ; 

 the lower portion, from the tongue of a lamb. 



No. 12. Branched muscle, ending in stellate connective cells, from the upper-lip of 

 the rat. 



No. 13. Black pigment-cells from the human eye, lining the internal surface of the 

 eye, magnified 150 diameters. 



* From jStos, life, and \oyos, discourse a discourse on life ; a more expressive 

 term than physiology. 



f From to-ros, a tissue or web, and \oyos, a discourse. 



