A GENE'nCO-PHISIOl-OOICAL STUDY ON THE FORMATION ETC. 77 



ill some resjÄcts. Certain antliüi's go so fiir as to regard the browuLsIi pigments 

 in the seed coat of the legumes as a soii; of pbiut melaniuic pigment.' 



■\VRiGirT (1917)', proix)sed an hypothesis regarding the colour inheritance 

 in Mammals. He pro^xises fii3t, that melanin is produced l\v the oxidation 

 of certiiiu products of protein metalxilism b}- the action of sfÄcific enzymes; 

 second, that this i-eaction takes place in the cytophism of cells probably liy 

 enz3-mes secreted by the nucleus ; third, that various chromogens are used, the 

 jiarticular ones oxidized depandiug on the charactere of the enzymes present, 

 and finally that hei^editaiy difference in colour are due to hereditary difierences 

 in the enzyme element of the reaction. It is supposed that color depends on 

 the rates of production or of potency of two enzymes. Enzyme I is essential 

 to the production of any colom-, but by itself only produces yellow. Euz^-me 

 n is supplementary to enzyme I, jiroducing no effect In- itself. The compound 

 euzj-me I — 11 is also more efficient than enzyme I in another way. It pr(.)- 

 duces sepia pigment even when enzyme I is at too lo\\- a potency to produce 

 anj- yellow by itself. Above th^ level at which enzyme I produces eflects, the 

 enzyme I and I — II, complete the oxidation of chromogeu. 



Regarding the place of the enzyme reaction to the chromogenic substance, 

 his liyix)thesis may be refen-ed to the -view of Unna (1913)' in which he 

 maintained that in the tissue of the animal skin, the plasma is the reduction 

 phxce (" Reduktiousort ") and the nucleus, the oxidation place (" Sauei-stoflbrt "). 

 In plants, however, Schneider (1914)* coiUd not establish Unna's ■\-iew.''' 



If the mitochoncWa is tha seat of the pigment synthesis as Guilliekmond 



1. JIaxk, a.. Coloration of the Seed Coat of Cowj^eas. Jour. Agrip. Eesearcb. 2 : 33, 1914. 

 The substances known as " Phytomelan " are, however, different from phlobaphenes. See Dafekt, 

 F. AV. and Miklauz, R., Untersuchungen ueber die kohleähnliche Masse der Kompositen. I. 

 Denlcschr. d. Kais. Akad. d. Wien. Bd. S7, 1911. Cited in JIolisch, H.. Mikrochemie der Pflanze. 

 1>. 319, 1913. 



2. Wkight, S., Color Inheritance in Mammals. Jour, of Heredity. 8 : 224. 1917. 



3. CssA. P. G., I3icxhemie der Haut. Jena. 1913. 



4. ScHXEiDETi, H, I'eber die Unnaschen Methoden zur Feststellung von Sauerstoff-und 

 Keduktion-Orten u. ihre Anwendung auf Pflanzliche Objekte-Benzidin als Reagens auf Verholzung 

 Zeitsch. f. wi.s.s. Mikro. Tech. 31 : .51, 1914. a. — Sohsetdeb. Neue Studien zur Parstellimg der 

 r.cduktions u. Sauerstofforte der Pflanzenzelle. Ibid. 47S. 1914. b. 



5. Cf. OsTBKHAUT. W. J. V.. The Role of the Nucleus in Oxidation. Science. N. S. 46:3G7, 

 1917. 



