xi THE ALBUMINOIDS : GELATINE 565 



glutin-peptones. If, therefore, a gelatine-solution is acted upon by 

 any means by which albumins are converted into albumoses, it at once 

 loses its power of solidifying. This occurs, for example, if gelatine is 

 boiled at ordinary or at increased pressure with pure water as a rule, 

 it must be admitted that the reaction is not exactly neutral, and 

 therefore usually the action of dilute acids or of dilute alkalies comes 

 also into play or on boiling with acids or alkalies, or as the result of 

 peptic and tryptic digestion, and of putrefaction. All the processes 

 first convert gelatine into gelatoses, and the latter into further 

 dissociation-products. 1 But before the dissociation, just alluded to, 

 has occurred, there is a certain stage during which the gelatine has 

 only lost its power of gelatinisation, being otherwise unaltered, and 

 during this stage it may be compared with ordinary albumins which 

 have become denaturalised without having as yet undergone a further 

 dissociation. Kept at body temperature gelatine-solutions lose their 

 power of gelatinising as a rule fairly quickly, sometimes in one to two 

 days. 2 



Injected subcutaneously, and even more so when injected intra- 

 venously, gelatine gives rise to certain symptoms of poisoning, apart 

 from acting on the blood. Whether these effects depend upon 

 impurities or whether they are due to the gelatine itself is as yet 

 uncertain. 3 



Different kinds of Collagen 



The gelatine described above may be obtained from connective 

 tissues or tendons, but the collagen in the cornea and the sclerotic coat 

 of the eye, discovered by Morochowetz, 4 and more carefully examined 

 by Morner, 5 and fish-gelatine, prepared from fish-scales by Weiske 6 and 

 Morner, 7 do not differ from the ordinary tendon-gelatine. The dried 

 corneal tissue contains 80 per cent, and that of the sclerotic 87 per 

 cent of collagen, according to Morner. The remainder is represented by 

 mucoid. The lens and the other parts of the eye contain no collagen. 

 Fish scales are composed of 20 per cent of ichthylepiden (see p. 578), 

 and 80 per cent of collagen, which is remarkable as the collagen is 

 very readily converted into gelatine. 



1 F. Hofmeister, Zeitschr. physiol. Ghem. 2. 299 (1878). 



2 C. T. Morner, ibid. 28. 471 (1899) ; A. Dastre et N. Floresco, Arch, de Physiol. 

 normcde et path. 27. 701 (1895). 



3 Compare different abstracts in the Zentrabl. f. d. Grenzgebiete von Med. u. Chir. 

 1902 to 1904 ; H. Kaposi, Heidelberger Habilitationsschrift, 1904. 



4 L. Morochowetz, Verhandl. des naturh.-med. Vereins zu Heidelberg, N.F. I., p. 480, 

 (1876). 



5 C. T. Morner, Zeitschr. f. physiol. Chem. 18. 213 (1893). 



6 H. Weiske, ibid. 7. 466 (1883). 7 C. T. Morner,' #wZ. 24. 125 (1897). 



