De Zouche. — Bacteria and their Relation to Disease. 35 



tumor, cum caloro et clolore." To be brief, the redness is due 

 to increased flow of blood to the part, the heat to increased 

 oxidation of tissue, and the pain to pressure on nerve-endings. 

 The smaller blood-vessels, termed capillaries, dilate, yet the 

 blood flows slowly, and has a tendency to stagnate. The 

 swelling is caused partly by the increased blood-supply, and 

 partly by the pouring-out from the capillary blood-vessels of a 

 thickish, glutinous, watery fluid termed liquor sanguinis, or 

 lymph, which under certain conditions becomes changed into 

 matter or pus. The examination of lymph showed it to con- 

 sist of water, albumen, fibrin, and salts, while under the 

 microscope could be seen spherical nucleated cells termed 

 lymph-corpuscles, which are identical with white blood-cor- 

 puscles. 



The origin of white cells in the liquor sanguinis thrown out 

 by the blood-vessels in inflannnation was by no means clear, 

 but a discovery of the highest importance, destined to throw- 

 light on this matter, was made by Dr. William Addison, of 

 Malvern, about the year 1843. This was one of the great dis- 

 coveries in physiology or pathology, and deserves special men- 

 tion. Dr. Addison saw the white corpuscles migrating from the 

 minute blood-vessels into the tissues outside. His observa- 

 tions were published in the Transactions of the Provincial 

 Medical and Surgical Association of 1843 and 1844*, w^hich 

 can probably be only found in some of the large medical and 

 scientific libraries in the United Kingdom or in the United 

 States, so that I am unable to give any details of his work. 

 His discovery was fully confirmed in 1846 by Dr. Augustus 

 Waller, an English physiologist, who watched the process of 

 inflammation in a frog's tongue placed under the microscope. 

 His method and description are very complete, and the 

 illustrations give great exactness to them. The mere exposui'e 

 of the tongue speedily excited inflammation, so that he had 

 the opportunity of seeing the increased flow of blood, and tlie 

 process of exudation of liquor sanguinis ; and now he was 

 able to see the white corpuscles moving slowly against the 

 wall of the small blood-vessels, then coming to a standstill, 

 and finally squeezing themselves through the coats of tlie 

 vessels with their peculiar amoeboid mode of progression, 

 first forcing an arm through, and then, by degrees, the whole 

 body, while the hole through which they had emerged closed 



*(1.) William Addison, M.D. "Experimental and Practical Re- 

 searches on the Structure and Function of Blood-corpuscles, on In- 

 flammation, and on the Origin and Nature of Tubercle in the Lungs." — 

 Prov. Med. Surg. Assoc. Trans., vol. xi., 1843, p. 233. (2.) " The Actual 

 Process of Nutrition in the Living Structures demonstrated by the 

 Microscope, and the Renewal of the Tissues and Secretions from the 

 Blood thereby illustrated."— Op. cit., vol. xii., 1844, pp. 235-306. 



