352 Referate 



On the other hand a sufficiently huge number of violet species crosses 

 give fertile offspring to have yielded results of great interest, both to 

 systematist and geneticist. A great many violets are naturally cleistogamous 

 and this leads to automatic elimination of heterozygotes. It has been an 

 immense amount of work, therefore, to have found between 60 and 100 

 natural hybrids that show segregation and recombination of one or more 

 allelomorphic pairs, and from the facts thus obtained to establish parentage 

 as weil as to contribute to our knowledge of inheritance. Besides these 

 numerous combinations that have proved heterozygous in at least one 

 factor, something over 100 anomalous forms constant in their characters 

 have been found. Argueing from his knowledge of the characters ot the 

 species with which they have been found and the behavior of the latter 

 in crosses, the author has been able to point out the e.xact character 

 recombinations possessed by the aberrant forms, and to show that they 

 are homozygous types resulting from the remote or recent hybridization 

 of older species. Thus he has been able to show a true evolution of new 

 forms of Viola in the wild by hybridization. 



The allelomorphic pairs whose behavior he has been able to establish 

 more or less definitely are as follows. Black seeds and brown seeds are 

 dominant to yellow seeds and black is apparently epistatic to brown. 

 Purple capsules are almost completely dominant to green capsules. Pube- 

 scence, undissected leaves, and broad cordate leaf shape are imperfectly 

 dominant to glabrousness, dissected leaves and lanceolate leaf shape. 



Besides the clean segregation of these characters, there was evident 

 segregation from complex relationships of leaf size, erectness of plant, 

 •color of flower, size of capsule and size of seed. E. M. East. 



Hagedoorn, A. L. Oordeelkundige Zaadteelt en fokkerij. Flakkeesche Boek- 

 en Handelsdrukkerij, Middelharnis, 1912, 95 pp. 

 Dieses Buch wurde im Auftrage der ,,Hollandsche Maatschappij van 

 Landboun" geschrieben. Es beabsichtigt eine gemeinverständliche Dar- 

 stellung von unsrer heutigen Kenntnis der Erblichkeitserscheinungen für 

 die Tier- und Pflanzenzüchter zu geben. Dieselben können aus der klar 

 geschriebenen Arbeit lernen, in welcher Weise rationell gezüchtet werden 

 muß und was dabei zu erhalten ist. Eine große Anzahl Beispiele aus der 

 Praxis erläutert die theoretischen Auseinandersetzungen. 



Tine Tammes, Groningen. 



