APPENDIX. 677 
mose and hemialbumose both result from peptic digestion, and it is 
assumed that these both split up into two molecules of antipeptone or 
hemipeptone, accordirig as the digestion is either peptic or tryptic. Evi- 
dently, trypsin carries the processes much further than pepsin. 
VIL. Lardacein (Amyloid Substance). 
This body is not found in the tissues in health, but results from a 
pathological process, and is most frequently found in the spleen, liver, 
kidneys, lungs, blood-vessels, etc. It consists of CHNO and a little sul- 
phur in some oxidized form. It is insoluble in water, dilute acids and 
alkalies, and neutral saline solutions. Like other proteids, it can be con- 
verted into acid-albumin and alkali-albumin; but, unlike all other pro- 
teids, it is not affected by the digestive juices. It may be recognized by 
giving a red color with iodine, and a violet or blue when heated with 
iodine and sulphuric acid. 
Weare still in ignorance of the real molecular constitution of pro- 
teids, and our whole knowledge of this class of bodies is in the empirical 
rather than the scientific stage. 
NirrRoGENoUS NON-CRYSTALLINE BODIES ALLIED TO PROTEIDS. 
These bodies resemble each other much less than the proteids proper : 
1. Mucin (CHNO). 
It is the characteristic body of mucus, which abounds in the bile of 
the gall-bladder and in snails, from either of which it may be prepared. 
It may be precipitated from its solutions by alcohol, alum, mineral acids, 
and acetic acid. The precipitate is dissolved by excess of mineral acids, 
but not by acetic acid, so that the latter forms one of the best tests for 
mucin. 
2. Chondrin (CHNOS8). 
This substance may be extracted from hyaline cartilage, and less 
easily from elastic cartilage. It readily gelatinizes from its solutions on 
standing; is soluble in hot water, alkalies, and ammonia; insoluble in 
cold water. Itis very doubtful whether chondrin of itself exists in car- 
tilage; it is more likely an allied product. 
3. Gelatin, or Glutin (CHNOS). 
This substance may be obtained by heating connective tissue for days 
with dilute acetic acid at about 15°, or by prolonged treatment with 
water under high pressures. It forms, when not pure, the well-known 
“glue.” Though swelling in cold water, it does not dissolve, but is 
readily soluble in warm water. It forms insoluble precipitates with tan- 
nic acid and mercuric chloride. 
4, Elastin (CHNO). 
This is one of the most insoluble substances derivable from animal 
tissues. It, however, yields to concentrated nitric and sulphuric acids 
in the cold and to boiling alkalies, and may be precipitated from its solu- 
tions by tannic acid. The substance is best obtained from the liga- 
mentum nuche of the ox. 
