Vererbung, Variation, Mutation. 267 



ein ergänzender zweiter, zu seiner Manifestation unerläßlicher, also „aktivie- 

 render" Faktor fehlt, oder weil in anderen Fällen ein gegensinniger, hem- 

 mender Faktor vorhanden ist, sondern die Manifestation eines Merkmales 

 kann auch ausbleiben, während die zur Reaktion nötigen Komponenten vor- 

 handen sind, und nur die Wechselwirkung zwischen diesen Faktoren aus- 

 bleibt. Es fehlt die typische „Assoziation" der Faktoren, die eben (bei dieser 

 Art von Cryptomerie) das Sichtbarwerden des Merkmals bedingt. Die Ursache 

 dieser dissoziativen Cryptomerie ist unaufgeklärt. Sie mag physikalischer 

 oder chemischer Natur sein. Mit „Latenz" ist der Begriff der Cryptomerie nicht 

 identisch. 



Bezüglich der Bedeutung der Cryptomerie für die Erklärung von Atavismen 

 und Mutationen, sowie bezüglich experimenteller Belege zu obigen theoretischen 

 Erwägungen sei auf die Arbeit des Verf. verwiesen: „Bastardierungsversuche an 

 Levkojen" usw. in Zeitschr. ind. Abst.-Vererbungsl. Bd. 7, 1912, sowie Zool. Zen- 

 tralbl., Bd. 2, Ref. Nr. 808. Daiber. 



802) White, D. E., Swingle on Variation in F x Citrus hybrids and the 

 theory of zygotaxis. In: Amer. Naturalist, Bd. 48, Heft 3, S. 185 — 192, 

 1914. 



Citrus aurantium (the orange) has been grown from seed in Florida for two 

 centuries and remained true. When crossed whith C. trifoliata, Swingle obtained 

 F 1 families showing a large amount of variability in foliage, habit, and especially 

 in fruit. The fruits differed in colour, shape and markedly in taste. When 

 varieties of the lemon were crossed with C. trifoliata, the Fj varied still more 

 widely. The writers criticism is that the races used in the cross could not have 

 been breeding true, since over 70 varieties of sweet orange alone are grown in 

 the United States. The theoretical explanations of F x variability offered by the 

 auf hör are also discussed. Gates. 



803) Bisset, Peter, The James River Wal nut. In: Journ. of Heredity, Vol. V, 

 Nr. 3, S. 98—102, 1914. 



A description is given of a remarkable tree on one of the old Virginian estates. 

 The tree is probably a cross between the native butternut walnut (Juglans cinerid) 

 and the Persian, or so called English, walnut [Juglans regia). It is of extraodinarily 

 rapid growth and remarkable vigor but the productivity is slight and the nuts 

 of no commercial value. A young tree near by raised from a seed borne by the 

 old tree and planted about 1860, exhibits the same characteristics as the parent 

 tree except that the young twigs are heavily covered with pubescent hairs which 

 it would seem to have inherited from the butternut parent. Pearl. 



804) Swingle, W. T. and Kellerman, Maud, Citropsis, A New Tropical 

 African Genius Allied to Citrus. In Jcurn. of Agr. Research, Vol. L, Nr. 5, 

 1914. 



African cherry oranges have formerly been wrongly classed in the Asiatic 

 genus Limonia. The authors now class them in a new genus, Citropsis, because 

 the species of this type are closely and clearly related to Citrus. The characters 

 distinguishing the species of Citropsis are given. The possibilities in grafting and 

 hybridizing Citropsis open up a new field for the plant breeder. Pearl. 



805) Hus,Hensi, The origin of X Capsella bursa-pa storis arachnoidea. 

 In: Amer. Naturalist, Bd. 48, Heft 4, S. 193—235, 1914. 



