Varietäten, Descendenz, Hybriden. 117 



years ago. Experience witli various compositae throws doubt on 

 such an opinion, because in diverse but more or less related genera 

 certain collarette variations appear. These variations, occurring in 

 Dahlia, Helianthiis, Ratihida etc., run closely parallel. The firßt 

 collarette sunflower of the chestnut and vinous forms of Helianthus 

 annimSj was obtained in 1915. Quite unexpectedly a considerable 

 number of plants showed this character, but the supplementary 

 lobes were narrow and very variable; somewhat afterw^ards a vfild 

 plant of H. afDiHUs lenticularis was found with genuine collarette 

 characters. An individual of Arnica pedunculata Rydberg, called 

 nov. var. Uihularis, found also in 1915, shows strong tendencies to 

 become collarette. 



The latest and in some ways most surprising collarette to be 

 discovered is in the long headed cone-flower, Ratihida columnifera. 

 This form (var. nov. appendicidata) was found in Juli 1916. The rays 

 possess long appendages, usually a pair, arising from the throat, 



These parallel variations do suppose that the genetic composition 

 of the whole group of genera is such that these particular changes 

 arise from time to time, without reference to the environment. 

 Whether, in any give case, they are due to original variations of 

 the germinal substance, or are due to the cropping out of charac- 

 ters for which determiners have existed in the chromosomes for 

 ages, may be extremely difficult to decide. 



M. J. Sirks (Bunnik). 



Collins, G. N. and J. H. Kempten. Patrogenesis. (Journ. of 

 Heredity. VII. p. 106—118. 1916.) 



A cross between Tripsacum dactyloides female, and Euchlaena 

 tnexicana male, has been carried through three generations without 

 exhibiting any indication of the characters of the female parent. In 

 attempting to explain this complete absence of the characters of 

 the female parent two alternatives may be considered. 



1. The characters of the female parent have been completely 

 masked by those of the male, or 



2. The male nucleus developed in the ovary to the complete 

 exclusion of the female, representing in a way the counterpart of 

 parthenogenesis. 



In the three generations of the progeny of this hybrid at least 

 350 plants have been examined. This and the fact that a great 

 variety of conditions has called forth great Variation and induced 

 many abnormalities without evoking any indication of Tripsacum 

 characters has caused the first alternative to be dismissed. If the 

 second alternative be adopted we are compelled to look upon the 

 results of this cross as special type of inheritance not previously 

 recognized. Hybrids showing a predom.inance of the characters of 

 the male parent have been described as petroclinous, but in this 

 cross and its successive progenies no trace of the characters of the 

 female parent has been detected. No true hybridization or conjuga- 

 tion between the two nuclei appears to have taken place. For this 

 form of false hybridization the name patrogenesis is proposed. The 

 term patrogenesis would also serve to place the phenomenon in 

 proper contrast with parthenogenesis. This is rendered appropriate 

 by the occurrence of what appears to be true parthenogenesis in 

 Tripsacum, when pollinated with maize. M. J. Sirks (Bunnik). 



