Botany. — " Cytological investigations on Apogamy in some elemen- 

 tdry species of Erophiki verna" . By J. P. Bannier. (Commu- 

 nicated bj Prof. F. A. F. C. Wknt). 



(Communicaled at the meeting of March 24, 1923). 



After Jordan, in 1823 '), made his well-known communications 

 concerning tlie constancj' of the elenientarj- species, and in particular 

 those of Erojihila verna, this highly poljniorphic species became not 

 merely the classic type of absolute constancy of the elementary 

 species, but also the subject of much experimental research. The 

 best known work on this subject is that of Rosen on the formation 

 of new sub-species by cross-fertilization. According to this writer 

 the hybrids do not conform to the laws of Mendei,, but, after having 

 formed a very heterogeneous F, remain constant in the F, and 

 following generations'). The explanation of this can only be found by 

 cytological research, accompanied by repeated efforts at hybridization. 



The investigations, the principal results of which so far obtained 

 are given here below, were prompted by similar attempts at hybri- 

 dization, carried out by Dr. J. P. Lotsy between two elementary 

 species found near Benuebroek, and further cultivated constant by 

 him, which, as they could not be identified with absolute certainty 

 with any previously described sub-species, were christened Erophila 

 cochleoides and Eropkila violaceo-petiolata. These experiments, however, 

 were unsuccessful in so far as no hybrids resulted from a cross- 

 fertilization, but all the offspring were like the mother plant, and 

 remained constant in following generations. 



One plant only, at first regarded as a hybrid, was a very fine 

 intermediary between the two aforesaid sub-species, but further 

 cytological examination proved that it could not be a hybrid result 

 of the applied cross-fertilization. The following generations of this 



1) Alexis Jordan. Remarques sur le fail de {'existence en société, a l'état 

 sauTage, des espèces végétales affines et sur autres fails relatifs a la question de 

 l'espèce. Buil. Ass. franc. Avanc. des Sciences Lyon 1873. 



'j Felix Rosen. Die Entstehung der elementaren Arten von Erophila verna. 

 Beitr. z. Biol. d. Ptl. 1911. Bnd. X. p. 379—421. 



23* 



