ABORTIVE OVULES 73 



cent., differed from the type, and had this character more or 

 less imperfectly developed. Under cultivation the seedlings 

 of Primula sinensis often have one of the cotyledons deeply 

 bifid; in one lot of seedlings this was the case with, for 

 instance, over 20 per cent, of the plants. 



In Poterium Sanguisorba the calyx-tube generally contains 

 one, but sometimes two or even three achenes. In Ranunculus, 

 occasionally, the petioles of the cotyledons are connate. 



In (Enothera the cotyledons are either straight, or with 

 one or both involute. Irmisch states that the cotyledons of 

 Clematis recta, which are usually aerial, sometimes remain 

 below ground ; while the reverse is the case in Melittis, arid, 

 according to Winkler, in Dentaria and Mercurialis, for the 

 cotyledons, which are generally fleshy and subterranean, 

 sometimes rise above ground and form small green leaves. 



Many species occasionally have one or both cotyledons 

 divided. 1 



In Eheum the cotyledons are generally parallel, but in 

 some cases one of them is placed more or less obliquely with 

 reference to the other. 



In Fagopyrum the position and arrangement of the coty- 

 ledons in the seed vary greatly. The cotyledons are turned 

 about after striking into an angle of the seed, and then, follow- 

 ing the testa, assume very various positions. In Carum Carui 

 the cotyledons sometimes have their backs to the axis of the 

 fruit, and sometimes their edges, while at others they are oblique. 



In Cheiranthus pygmaeus the cotyledons are said to be 

 sometimes accumbent, sometimes incumbent, and straight or 

 convolute, even in the same pod. 



It would be easy to multiply such cases, but I will only 

 mention one more, in which I will venture to suggest a reason 

 for the variation. In Acer (fig. 118, i), the embryo originates 

 in a short tubular cavity opposite the micropyle, and is at 

 first straight, with an extremely short turbinate radicle, and 

 ovate, obtuse, closely adpressed cotyledons. As growth con- 

 tinues the embryo extends itself along the lower side of the 

 seed, and curves with it, becoming gradually lanceolate, or 



1 See Goebel, Grundziige Syst. Spec. Pflanzen- Morphologic, p. 505 ; or 

 Eng. trans., Outlines of Classification &c. p. 446. 



