244 



Scientific Proceedings (115). 



of the orange peel are rich in the fat soluble vitamine. On this 

 diet young rats have matured, mated, and raised young. Control 

 experiments showed the diet, without the preparation of orange 

 peel, to be free from fat soluble A. 



Experiments now in progress indicate that similar preparations 

 made from lemon and grape fruit peel likewise contain the fat 

 soluble vitamine. 



A detailed account of the experiments will appear in the course 

 of the year. 



123 (1705) 



Effects of age and of the inclusion of salts on the heterotropic 

 action of colloidal bodies of cytological interest. 



By D. T. MACDOUGAL. 



[From the Desert Laboratory, Tucson, Arizona.] 



Auxographic measurements of the swelling of sections of 

 dried plates of agar and of gelatine previously described show 

 that the relative enlargement of a colloidal body in its different 

 axes will be determined largely by the unequal stresses which may 

 be set up, as for example when liquid agar or gelatine is poured 

 on glass and dried without shrinking in area. It was pointed out 

 that sections from such plates of agar increased only 3 or 4 per 

 cent in length while swelling 3,000 or even 4,000 per cent in thick- 

 ness, and that sections of gelatine increased 8 to 40 per cent in 

 length while swelling from 500 to 2,000 per cent under the auxo- 

 graph. 1 



Tests of sections of plates of pure agar freshly made and a 

 year old have recently been made. Plates which swelled 2,000 

 per cent in water when freshly made August 1, 191 9, increased 

 but 1,600 per cent July 1, 1920. Plates swelling 3,200 per cent 

 when young increased but 2,000 per cent when nine months old. 

 This total decrease was accompanied by lessened swelling in thick- 

 ness and increased swelling parallel to the broad surfaces of the 

 plates. The relative increase in length and width of sections of 

 old plates was double that in the same plates when newly made 



1 MacDougal and Spoehr, "Hydration of Amino Compounds," Proc. Soc. 

 Exper. Biol, and Med., 1919, xvii, 33-36. 



