326 RETROGRESSIVE CHANGES 



diffusion of water into this area, with consequent swelling, and 

 often a lifting up of the skin in the form of blisters. 



Bmphysematous gangrene, 1 usually produced by gas- 

 forming anaerobic bacteria, particularly by B. aerogenes cap- 

 sulatus, may also possibly be produced by B. coli communis in 

 diabetic patients in whose blood and tissues there may occur 

 sufficient sugar to permit of gas-formation. Hitschmann and 

 Lindenthal 2 found that the gas produced in cultures by an 

 anaerobic organism which they isolated from a case of emphysem- 

 atous gangrene, consisted of 67.55 per cent, hydrogen, 30.62 

 per cent, carbon dioxide, and traces of ammonia and nitrogen; 

 this corresponds to the statement of Welch and Nuttall that the 

 gas in the tissues of infected animals is inflammable. Dunham 3 

 found that the gas produced by B. aerogenes capsulatus in cul- 

 tures has the following composition : Hydrogen, 64.3 per 

 cent.; carbon dioxide, 27.6 per cent.; other gases, probably 

 chiefly nitrogen, 8.1 per cent. 



RIGOR MORTIS 4 



This topic may be appropriately considered in connection 

 with cell death, since it is a characteristic change occurring after 

 general death. All forms of muscle, striped, smooth, and car- 

 diac, undergo this change, which is shown by a shortening and 

 thickening of the muscle, which also becomes opaque and hard. 

 Rigor mortis begins first in the heart muscle, according to 

 Fuchs, 5 but it is generally observed first in the eyelids, then in 

 the muscles of the jaw, from which point it proceeds down- 

 ward, although the upper extremities may not become rigid 

 before the lower. The time of onset is extremely variable, but 

 the following general rules may be stated : All conditions 

 that lead to excessive muscular metabolism, with its resulting 

 increase in the acidity of the muscle fluids, will hasten the 

 onset of rigor mortis ; thus, people killed suddenly during violent 

 activity may remain almost in the position in which they met 

 death. Acute fevers, strychnine poisoning, tetanus, etc., cause 

 likewise a rapid onset of rigor, which may, indeed, appear 

 almost simultaneously with death, or even before the heart has 

 stopped beating. When a healthy individual meets death with- 



1 Complete literature by Fraenkel, Ergebnisse der Pathol., 1902 (8), 403 ; 

 and by Welch, Johns Hopkins Hosp. Bull., 1900 (11), 185. 



2 Quoted by Fraenkel. 



3 Johns Hopkins Hosp. Bull., 1897 (8), 68. 



* Literature, see v. Fiirth, Ergeb. der Physiol., Abt. 1, 1902 (1), 110; and 

 references cited in text. 



5 Zeit. f. Heilk., 1900 (21, Path. Abt.), 1. 



