56 SUBCELLULAR PARTICLES 



granule might be derived by application of the matrix concept to the chemical 

 and physical constitution of the melanoblast. 



Oxidative Polymerization of Catechol in Mineral Systems. A catechol-protein 

 system antecedent to the study of polyquinones is still under investigation, 

 presenting more complexities in analysis than did the latter. It may be pointed 

 out, however, that even at pH 8.8, where catechol oxidation has been followed, 

 the polymeric products thus far isolated from fibrin, collagen and gelatin sys- 

 tems dififer little from one another but markedly from material formed by pro- 

 tein-free controls in yield, visible absorption spectra and magnitude of spectral 

 shifts between pH 1.5 (orange color) and pH 8.8 (green color). There are two 

 features of interest in association with the catechol-mineral system. First, it pro- 

 vides a three-way connection, linking the eugenol-mineral system, from which 

 it was derived, both to quinone-protein systems just considered and to pyrogallol- 

 inorganic substance systems, one of the classes of peroxidase models yet to be 

 discussed (fig. 5). Second, the catechol-mineral system provides additional evi- 

 dence for the matrix activity of inorganic substances, suggesting a role of possible 

 geochemical importance for them in the formation of organic polymers and the 

 origin and antiquity of specificity in polymer synthesis. 



The NaCl-precipitable products formed when o.im catechol solutions were 

 incubated at 25 °C for 100 hours were all dark-brown substances insoluble in 

 aqueous and neutral organic solvents (hence, originally dispersed as a hydrosol, 

 not as a true solution). Products formed in the mineral-free control system com- 

 prised 3 per cent by weight of the original catechol and averaged on analysis, C, 

 6o'/c ; H, 3.69^ ; those formed in the presence of minerals comprised 27-32 per 

 cent of the original catechol and averaged C, 47-547^ ; H, 3.0-3.3% (34). Ultra- 

 violet absorption characteristics were as follows: 



MINERAL SPECTRAL FEATURES Eiem'^ " 



None shldr. 275-280 m/x 260 



Chrysotile shldr. 265-270 125 



Granite max. 265 103 



Hornblende shldr. 275-280 411 



The study of mineral-catalyzed and directed polymerization has been shown 

 to be of utility in development of the matrix concept, and prompted further 

 examination of the catalytic oxidation of phenols. Because it is more readily 

 oxidizable than the other phenols studied, pyrogallol was introduced as a sub- 

 strate. At the same time, the desire that the matrix itself be simplified prompted 

 the introduction of free elements as well as inorganic compounds. The new ex- 

 perimental system thus constituted led to the development of one of the two 

 classes of peroxidase models now to be described. The other class of peroxidase 



