194 ANIMAL PHYSIOLOGY. 
tetanus. It was, therefore—putting all the facts together that 
we now refer to and others, not forgetting that a muscle is 
always respiring, inhaling oxygen, and exhaling carbonic an- 
hydride—not unreasonable to conclude that normal tetanus 
and rigor mortis were but exaggerated conditions of a natural 
state. The coagulation of the muscle protoplasm (plasma), 
giving rise to myosin, was, however, a serious obstacle to the 
adoption of this view. But it has very recently been urged 
with great plausibility that an old view is correct, viz., that 
rigor mortis (contracture) is the last act of muscle-life; it is, in 
fact, a prolonged tetanus or contracture, ending in most cases, 
though not all, in coagulation of the myosin. This state can 
be induced and recovered from in favorable cases by cutting 
off the blood from a part by ligature, and later readmitting it 
to the starving region. It has been suggested that the prod- 
ucts of the muscle-waste, usually washed away by the blood- 
stream, in such an experiment and after death, collect and act 
as a stimulant to the muscle, causing it to remain in permanent 
contraction. 
The other constituents of dead muscle and their relative 
properties may be learned from the following table (Von Bibra): 
PW ALGT fo scccsand o's ae = cece aye Soars Holes ath, e%ae ane wrd ao ale V44'5 
Solids: Myosin, elastic substance, etc., in- 
soluble in water...........c0ceee sees 155°4 
Soluble proteids................-... 008. 19°3 
Goel ating sa taiaa einai ede cise aloes 20°7 
Extractives and salts............. ah 387'1 
Ma GS inc: wa seibcavesnieca diate he were nue eleraes me hee Bey 23°0 
255 5—255'5 
Aha lissiaigeedsnetee cOnrae i actuate sana se 1,000 
Among the extractives of muscle very important is creatin 
(‘2 to °3 per cent), a nitrogenous crystalline body. Certain 
allied forms, as xanthin, hypoxanthin (sarkin), karnin, taurin 
and uric acid, are also found. 
Glycogen (animal starch), very abundant in all the tissues, 
including the muscles of the embryo, is found in small quantity 
in the muscles of the adult; and in the heart-muscle a peculiar 
sugar (inosit) is present. 
It is, of course, very difficult to say to what extent the bodies 
known as extractives exist in living muscle, though that glyco- 
gen, fats, and certain salts are normally present admits of little 
doubt. 
