89 



separated, though this is not abundant. Filtering and further boiling 

 produces no further precipitation, but the addition of nitric acid drop 

 by drop gives a heavy flocculent precipitate. The clear aqueous ex- 

 traction noted above, slightly acidulated with hydrochloric acid and 

 heated, shows a shght turbidity just before reaching ihe boiling point, 

 f Pooling and the further addition (jf the acid produces at once a heavy 

 flocculent precipitate, which dissolves u| on heating and reappears upon 

 cooling. 



A solution of sodium carbonatf (0-5 per cent.) added to the clear 

 aqueous extract of the dried latex produces an immediate turbidity 

 which, upon heating, separates into a small amount "f fine precipitate. 

 From these last re-ults ii will be seen that the soluble albumins of the 

 latex of the papaw are only parti.illy coagulated by heat. 



When c rcentrated hydrochloric acid is caution --ly added to the 

 clear watery extract of the latex, there is formed a heavy curdy 

 urecipicate, solubl-^ in an excess of the acid. In a cL ar aqueous 

 solution of the latex, concentrated nitric acid producing a heavy 

 white precipitate, also soluble in an excess of the acid (proteid reac- 

 tion). This precipitate turns yellow and dissolves upon heating (albu- 

 mose,) but upon cooling is again precipitated. Upon adding an ex- 

 cess of acid, it is completely dissolved an 1 not re-precipitated when 

 cooled (globulin^. 



The presence of soluble globulin in an aqueous solution is further 

 shown in that the precipitate produced by boiling is not soluble in 

 hydrochloric acid (0"2 per cent). 



The lesidue left upon the extraction of the dried milk with water 

 is partially soluble in a weak solution of common salt, and the result- 

 ing solution gives a precipitate with nitric acid (globulinj. 



Ihe watery solution noted above, when rendered slightly acid 

 (acetic) and bmled, is made turbid, forming small amount of floccu- 

 lent precipitate (globulin and albumin). 



The clear watery extract of the papaw latex, when saturated with 

 ammonia sulphate, gives an abundant white precipitate with strong 

 prot'id reaction (the precipitate carrying the greater portion of the 

 ferment). The precipitate just noted, freed from the ammonium sul- 

 phate, dissolved in water, made acid with acetic acid, and then satur- 

 ated with common salt gives a white flocculent precipitate (primary 

 albumose). After saturation with ammonium sulphate, the filtrate 

 gives a precipitate, deutero-albumose, and the supernatant liquid, 

 under the biuret test, shows the presence of peptones. ^ ^ If precipi- 

 tated by soda-magnesium sulphate, the filtrate likewise exhibits a 

 strong peptone reaction. ^^ 



ANALYSIS OF PAPAW PROTEIDS. 



It cannot be said that any of the enzymes have been comph tely iso- 

 lated. The most that can be urged is that the enzymes are either 

 proteid in character, or are associated with proteid bodies In all, or 



(15) By the digestion of a solution of this peptone with the separated ferment 

 or with trypsin, leucin and tyr.'sin appear (indicating henaipeptone). 



(16) The classification of the albunioses and peptones is the subject of contro- 

 versy. The classification here followed is that in most common use. Under 

 another view we would have in this substance a mixture of globulin, proto and 

 deutero albumose with, possibly, two or more forms of peptone. 



