674 ANIMAL PHYSIOLOGY. 
III. Globulins. 
This class of bodies is characterized by being insoluble in water, solu- 
ble in dilute saline solutions (especially sodium chloride) : soluble in 
dilute acids and alkalies, when they are transformed into acid-albumin 
and alkali-albumin respectively. Most of the globulins are precipitated 
by saturation with solid sodium chloride. 
1. Globulin (Crystallin).—When the crystalline lens of the eye is 
rubbed up with fine sand and extracted with water, upon filtration an 
‘passing a stream of carbon dioxide through the filtrate, a precipitation 
of globulin is obtained. Though strongly resembling paraglobulin and 
fibrinogen, it is not known to favor fibrin-formation. 
2. Paraglobulin (Fibrinoplastin).—This body may be obtained from 
blood-serum by passing through it a current of carbonic anhydride, 
when a flocculent precipitate falls, which later becomes very finely gran- 
ular, and may be separated by filtration. Addition of solid sodium 
chloride precipitates this substance only in part. It is very readily 
changed into alkali-albumin, and still more so to acid-albumin, by addi- 
tion of dilute alkalies or acids. This body is not easily precipitated by 
alcohol. Its coagulation-point is about 70° C. 
Paraglobulin has been found in blood-serum, lymph, chyle, serous 
fluids, the aqueous humor, the cornea, connective tissue, and in the pale 
and colored corpuscles. It occasionally appears in urine as a patho- 
logical product. 
3. Fibrinogen.—While greatly resembling paraglobulin in most 
characteristics, the coagulation-point is different, being 52° to 55° when 
in solution in dilute sodium chloride. It is not so readily precipitated 
from diluted solutions as the body previously described, and is viscous 
rather than granular. 
It may be obtained from blood-plasma by: special precautions, though 
more readily from hydrocele-fluid. Fibrinogen occurs in blood, chyle, 
serous fluids, and numerous transudations. It has been considered by 
many observers to be essential in the formation of fibrin. 
4. Myosin, as its name implies, is derivable from muscle-plasma, and 
may be regarded as the latter substance in an altered form. It may be 
prepared from washed muscle, by treatment with a ten-per-cent solution 
of common salt, and dropping the viscid product slowly into distilled 
water, when it falls as a flocculent, whitish precipitate. It is readily con- 
verted into syntonin (a form of acid-albumin, as has been pointed out) 
by acids, and into alkali-albumin by alkalies. In very weak acids and 
alkalies it is soluble without conversion into a different substance. The 
coagulation-point of myosin is low, 55° to 60° C. 3 
5. Vitellin.—This body, probably united with lecithin, is the chief 
proteid constituent of the yelk of egg, from which .it is usually prepared. 
It differs from most of the globulins in not being precipitated from its 
solutions by sodium chloride. The coagulation-point lies between 70 
and 80° C. 
6. Globin is a doubtful member of this class. It is regarded as tke 
