3 1 8 Vierte allgemeine Sitzung. 



gens represented in the germ cells, — against which assumption 

 we have here presented evidence — but, that each of these 

 representatives has such a narrow and cir- 

 cumscribed and integral existence in im- 

 mediate ancestors of this cell — we m i g h t 

 say in the chromosomes, or in a chromosome 

 of such cell — that the reduction divisions 

 shuffle it as an integer, and that from this moment 

 onward the cells arising from such division differ among them- 

 selves in such a l way that one wholly possesses a pro- 

 perty which the other wholly and forever lacks. 



Such conceptions do not seem to fit what we know of the 

 chemical origin of color, nor are they reconcilable with our know- 

 ledge of the physiology of color characters. On the contrary data 

 from these sources incline in quite the opposite direction. And, 

 to inheritance theory it makes all the difference in the world 

 whether we be permitted to think of the color character as being 

 represented by a wholly segregable particle, or group of 

 particles; or, whether we be forced to view such characters as 

 based not at all on particles, but upon a given strength of a 

 process, a property of whole cells. The-on e view leads straigh- 

 tway to the most rigid Preformation ; the other, to a measure of 

 Epigenesis that makes development a reality. 



Literature cited. 



1903. Cuenot, L. L'heredite de la pigmentation chez les souris. Arch. Zool. 

 Exp. 4, No. 3, p. 33. 



1904. Durham, F. On the Presence of Tyrosinase in the Skins of Some Pig- 

 ment- ed Vertebrates. Prelim. note. Proc. Roy. Soc. London, vol. 74. 



1909. R i d d 1 e , O. Our Knowledge of Melanin Color Formation and Its Bearing 



on the Mendelian Description of Heredity. Biol. Bull., vol. 16, No. 6. 

 1909 a. Wheldale, M. Royal Soc. Proc. B. vol. 81 and also Camb. Phil. 



Soc. Proc. vol. 15, Part. 2. 

 1909 b. Wheldale, M. Further Observations upon the Inheritance of flower 



color in Antirrhimim majus. Report to the Evol. Com. of the Roy. Soc. Report 5. 

 191 o. Gortner, R.A. A Contribution to the Study of the Oxidases. Trans. 



of the Chemical Society, vol. 97. 



Zu der nun folgenden Diskussion erbittet sich das Wort 

 Herr Prof. Dr. L. P 1 a t e (Jena) : 



,,Herr Kollege R i d d 1 e verwechselt, wie mir scheint, 

 zwei verschiedene Gebiete, die Presence and Abscence-Theorie, 

 welche nur ein besonderer Ausdruck der Mendel sehen Regel 

 ist, und den Nachweis von Enzymen, welche die Farben veran- 

 lassen sollen. Er behauptet, weil dieser Nachweis weder Miss 

 Durham noch ihm gelungen ist, deshalb soll jene Theorie irrig 



