686 C, M. LAPIERE AND J. GROSS 



TABLE III. COLLAGENOLYTIC ACTIVITY OF PROTEASES AND TiSSUE EXTRACTS 



" Collagen substrate in each tube contains 810 cpm. Total volume is 0.6 ml. 



'' Purified CI. histolyticum collagenase (courtesj- of Dr. P. Gallop) and crude tadpole 

 collagenase (lyophilized tail fin culture medium). 



■^ 100 jul of extract representing 20 mg of fresh tissue homogenate in 0.12 M NaCl + 

 0.008 M EDTA. 



•^ Excess of Ca^"*" added prior to assay. 



protease activity. Values greater than 1 which increase with time 

 of incubation are indicative of the presence of collagenase activity. 

 Extracts of fresh tail fin and back skin from nonmetamorphosing 

 and th)a-oxin-treated animals have, thus far, rexealed onh' proteohtic 

 type activity on collagen. 



