42 



Die Meinimg dass Knight, auf vergleichende Selbstbe- 

 stâubungs- und Kreuzungsversuche an Pisum gestùtzt, 

 schon lange zuvor den Satz aufgestellt hâtte, dass keine 

 Pflanze eine unbegrenzte Zabi von Generationen hindurch 

 sich selbst befruchte, moge also richtig sein, der Satz bat 

 aber einen anderen Sinn als D a r w i n's 1858 u. 1859 

 ausgesprochene Vermutung. D a r w i n's Praemisse, dass 

 eine lange fortgesetzte Selbstbefruchtung die Kraft und 

 Fruchtbarkeit der Pflanze herabsetzt, bat er nicht ausge- 

 sprocben. 



Was Herbert') betrifft, der an zweiter Stelle genannt 

 wird als Schriftsteller, der auf die Notwendigkeit der Kreu- 

 zung hingewiesen bat, muss bemerkt werden, dass er in 

 seiner Abbandlung ùber die Amaryllidaceae zwar die 

 Vermutung ausgesprocben bat, dass die Pflanzen obne 



J) Herbert. Amaryllidaceae, London 1837, p. 371. 



»I am inclined to think that I hâve derived advantage from 

 impregnating the flower, from which I wished to obtain seed, with 

 pollen from another individual of the same variety, or at least 

 from another flower, rather than with its own; and as races of 

 animais are known to degenerate, if they are perpetuated by the 

 unions of near kindred, it seems not unlikely that vigoiir may be 

 given also to any race of vegetables by introducing a cross, though 

 of the same kind, and especially from an individual grown in a 

 différent soil or aspect. To illustrate this, I will state a circumstance 

 which occurred last summer in my stove. Nine very fine crosses of 

 Hippeastrum were llowering there at the same time ; one a natural 

 seedling from Johnsoni or Regio-vittatum, two Johnsoni-pulverulen- 

 tum, one .... Being désirons of blending again thèse plants which 

 were ail cross-bred, différent flowers were touched with pollen 

 from their several neighbours and ticketed, and other flowers were 

 touched with their own pollen. Almost every ilower, that was 

 touched with pollen from another cross produced seed abundantly, 

 and those which were touched with ther own either failed entirely 

 or formed slowly a pod of inferior size with fewer seeds, the 

 cross imprégnation decidedly taking the head." 



