A GENETICO-PHISIOEOGICAL STUDY ON THE FORMATION ETC. 
77 
in some respects. Certain authors go so far as to regard the brownish pigments 
in the seed coat of the legumes as a sort of plant melaninic pigment. 1 
Wright (1917)', proposed an hypothesis regarding the colour inheritance 
in Mammals. He proposes first, that melanin is produced by the oxidation 
of certain products of protein metabolism by the action of specific enzymes; 
second, that this reaction takes place in the cytoplasm of cells probably by 
enzymes secreted by the nucleus ; third, that various chromogens are used, the 
particular ones oxidized depending on the characters of the enzymes present, 
and finally that hereditary difference in colour are due to hereditary differences 
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 colour, but by itself only produces yellow. Enzyme 
II i3 supplementary to enzyme I, producing no effect by itself. The compound 
enzyme I—II is also more efficient than enzyme I in another way. It pro¬ 
duces sepia pigment even when enzyme I is at too low a potency to produce 
any yellow by itself. Above the level at which enzyme I produces effects, the 
enzyme I and I—II, complete the oxidation of chromogen. 
Regarding the place of the enzyme reaction to the chromogenic substance, 
his hypothesis may be referred to the view of Unna (1913) ; in which he 
maintained that in the tissue of the animal skin, the plasma is the reduction 
place (“ Reduktionsort ”) and the nucleus, the oxidation place (“ Sauerstoffort ”). 
In plants, however, Schneider (1914) 1 could not establish Unna’s view. 6 
If the mitochondria is the seat of the pigment synthesis as Guilliermond 
1. Mann, A., Coloration of tlie Seed Coat of Cowpeas. Jour. Agric. Research. 2:33, 1914. 
The substances known as “ Phytomelan ” are, however, different from phlobaphenes. See Dafeet, 
F. W. and Miklauz, R., Untersuchungen ueber die kohleähnliche Masse der Kompositen. I. 
Denkschr. d. Kais. Akad. d. Wien. Bd. 87, 1911. Cited in Molisch, H., Mikrochemie der Pflanze, 
p. 319, 1913. 
2. Weight, S., Color Inheritance in Mammals. Jour, of Heredity. 8 :224, 1917. 
3. Unna, P. G., Biochemie der Haut. Jena. 1913. 
4. Schneider, H., Ueber die Unnaschen Methoden zur Feststellung von Sauerstoff-und 
Reduktion-Orten u. ihre Anwendung auf Pflanzliche Objekte-Benzidin als Reagens auf Verholzung. 
Zeitsch. f. wiss. Mikro. Tech. 31:51, 1914, a.— Schneider. Neue Studien zur Darstellung der 
Reduktions u. Sauerstofforte der Pflanzenzelle. Ibid. 478. 1914. b. 
5. Cf. Osterhaut, W. J. V., The Role of the Nucleus in Oxidation. Science. N. S. 46:367, 
1917 . 
