54^ Proceedings Cohimbia Biochemical Association [July 



These findings fail to support the concluslons of Rosenau and 

 Amoss,'^ but are in accord with, and extend, the observations of 

 Weisman.^ 



go. On the comparative physiology of creatin and Creatinin. 

 Max Morse. {Woods Hole, Mass.) In a study of the absorption 

 of the muscles in the tail of the larva of the common frog, attention 

 was directed to the creatin-creatinin content of the muscle and also 

 of the ehmination of these Compounds in the excretions. Numerous 

 attempts to determine the amounts led to the general conclusion 

 that, with the color reactions used (Folin-Benedict-Meyers method 

 and the older Jaffe reaction), no creatin or Creatinin is demonstrable 

 either in the fresh muscle or in the excretions. The results were 

 negative with Weyl's test and with Kramm's and Salkowski's 

 methods. 



An attempt to isolate the crystallin Compounds was futile. The 

 f ollowing method was used : The larva was weighed and measured ; 

 the tail was removed, ground in sand, covered with 95 per cent. 

 alcohol and shaken for two-minute intervals on an International 

 Instrument Company centrifuge-head shaker with four changes of 

 water. The liquids were mixed and made up to 100 c.c. Ten c.c. 

 portions were used for the various reactions. A Duboscq color- 

 imeter was used, but the readings were not recognizable in the 

 instrument. Excretions were caught by placing the larva in a large 

 petri dish with a measured amount of distilled water, the whole 

 being concentrated at low heat by evaporation. 



This Observation accords with other data showing that the ab- 

 sorption of the tail involving the disappearance of over a gram of 

 tissue within 12 hr. does not concern nitrogen elimination in excess 

 of the normal for non-metamorphosing frogs. 



The study of the creatin-creatinin content of tails and excreta 

 of metamorphosing frogs was inspired by the conclusions of several 

 workers on mammalian material, which seemed to show that muscle 

 metabolism, especially the atrophying muscle of involuting uteri, 

 etc., involved quantitative relations of these Compounds, but Mellanby 

 has more recently shown that this is not true for mammalian uteri. 



'Rosenau and Amoss : Journal of Medical Research, 191 1, xxv, p. 35. 

 ^Weisman: Biochemical Bulletin, 1913, ii, p. 295. (See also page 558 of 

 this issue. Ed.) 



