182 ON SEEDLINGS 



type occur irregularly in different individuals. There are a few 

 large openings in the mucro, confined to the very tip. 



The midrib in some cases forks a little way above the base of 

 the cotyledon, diverges and runs to the margin where each fork ends 

 in a mucro. Fission occurs between these two mucronate tips in 

 one, or occasionally both cotyledons while yet in the seed. After 

 germination the mucronate tip ceases after a time to elongate, and 

 growth of the surrounding tissue causes the emargination of both 

 halves of the cotyledon. In this case there is a median fissure, 

 and two shallower lateral ones. 



The forking of the midrib in other seedlings may arise below the 

 base of the lamina when the cotyledon becomes more or less deeply 

 bifid. Again this forking may be carried down so far that one 

 (seldom or never both) cotyledon is divided nearly to the base of 

 the petiole, when there appear to be three distinct cotyledons with 

 laminae and petioles. 



When the seed is carried up on the tips of 

 the cotyledons, the latter as they develop make 

 a great but unsuccessful effort to divest them- 

 selves of the now dried-up testa and remains of 

 the endosperm. The sides of the laminae become 

 revolute longitudinally at an early stage so as 

 to present their outer surface to the light. At 

 length only the tip of the cotyledons is held fast ; 



Primula smensis. , ,. . . , 7 , i -\ 



With bifid cotyledon, and the petioles twist so as to bring the upper 

 Nat. size. surface of the lamins outwards to the light. 



In deeply bifid cotyledons the division of the central vascular 

 bundle takes place low down in the petiole ; a branch runs down 

 the centre of each half to the apex, where it is tipped with a mucro. 



Stem short, stout, fleshy with scarcely developed internodes. 



Leaves coarsely hairy on both surfaces and dotted with sessile 

 glands, dull green above, paler beneath, sometimes suffused or 

 coloured brownish-red ; petioles semiterete, channelled above, 

 coarsely hairy and glandular, dilated and sheathing at the base. 



No. 1. Cordate, obtuse, five-nerved at the base, and alternately 

 penninerved upwards, becoming doubly dentate-serrate. 



No. 2. Cordate, subacute, lobulate with the lobes somewhat 

 dentate. No. 3 is similar, or more decidedly lobulate. 



Androsace rotundifolia, Hardw. (fig. 500). 

 Primary root quite normal. 



Hypocotyl very short, tapering downwards, slightly pubescent, 

 very pale and marked with red dots ; 1-5-2 mm. long. 



