Evidence of a Structure in Gelatin Gels. 257 

 114 (1861) 

 Evidence of a structure in gelatin gels. 1 



By ROSS AIKEN GORTNER and W. F. HOFFMAN. 



[From the Division of Agricultural Biochemistry, University of 

 Minnesota, St. Paul, Minn.] 



The question as to whether or not a colloid gel has a definite 

 structure is extremely important to the biologist because of its 

 bearing on the structure of protoplasms. 



Bancroft 2 recently reported some unpublished results of a 

 Mr. Cartledge in which gelatin gels of different concentration 

 were dried down to 96 per cent, gelatin and then these dried sheets 

 were allowed to again imbibe water. It was found that "each 

 swelled rapidly to the original concentration and then took up 

 water slowly," or in other words, a film of dried gelatin made 

 from 8 per cent, gelatin gel was still potentially an 8 per cent, 

 gel and very different from a dried film from a 16 per cent. gel. 

 Arisz 3 had previously reported data showing a marked difference 

 in imbibition capacity of gelatin gels of different concentrations 

 and also of discs of uniform concentration but of different thick- 

 ness. 



Inasmuch as the experiments cited by Bancroft have such a 

 profound bearing on all colloid-chemical studies in which gelatin 

 has been used, it appeared worth while to attempt to duplicate 

 Cartledge's results. Accordingly a series oi; gels was prepared 

 as follows: 



Weighed quantities (10, 15, 20, 25, 35 and 40 grams) of " Bacto" 

 gelatin 4 were added to 100 c.c. of distilled water in clean pyrex 

 flasks. After soaking for 15 to 30 minutse the flasks were placed 

 in a hot water bath and allowed to remain until all of the gelatin 

 had dissolved to form a homogeneous solution. A measured 

 quantity (25 c.c.) of this solution was then poured into petri 

 dishes 89 mm. in diam., thus ensuring the same thickness of the 



1 Published with the approval of the Director as Paper No. 311, Journal Series, 

 Minnesota Agricultural Experiment Station. 



2 Bancroft, W. D., "Applied Colloid Chemistry," 1921, p. 251. 



3 Arisz, L., Roll. Beth., 1915, vii, 51-6. 



4 Air-dry gelatin as received from manufacturer. 



