302 Mr Philip Sewell's Ohscrvaiions upon the 



cotyledons, and as to those features which may be considered 

 as especially characteristic of particular species. 



As may be seen by reference to the foregoing table, the 

 shape of the lamina of the cotyledon is approximately 

 rounded, but generally somewhat broader than long. In 

 some species there is a slightly emarginate apex, a feature 

 more or less shown by all when mature. 



The base of the lamina alters considerably in most of the 

 species as they develop. In some species it is a transition 

 from a slightly cordate base to one which merges gradually 

 into the petiole. In most the transition is such us may be 

 observed in the leaves subsequently developed, and is 

 towards a form with a broader base at a later period. 8. 

 ohovata and S. varicgata, S. Forskohlei and S. Tenorii were 

 decidedly cordate when the cotyledons expanded ; S. Heeriana 

 and S. runcinata retained abruptly straight bases ; ^S', 

 intemqota shewed a peculiar thickening of the base of the 

 lamina, causing a slight projection beyond the edge from the 

 under surface. 



These variations in shape of the cotyledon have probably 

 reference to the variations in shape of the cauline leaves, 

 an abrupt base or an attenuate apex, a long or a short petiole, 

 being frequently seen both in cotyledons, and, at least, in some 

 of the earlier subsequent leaves in certain of the species. 



More distinct than such variations in shape are the few 

 exceptions to the ordinary smooth type of cotyledons. S. 

 interrupta, in its two forms, possesses almost hirsute 

 cotyledons, in contrast to all the other species, just as 

 it shewed a larger nutlet and one without a mucilaginous 

 development in contrast with the rest of the species observed. 

 The cotyledons of S. interrujda possess long petioles, and 

 have much more the appearance of ordinary leaves than 

 have most, having an almost recognisable midrib or line of 

 venation through the fleshy lamina, in continuation with the 

 petiole. The cotyledons persisted in this species for a longer 

 time than was commonly the case amongst the others. 



The cotyledons of aS'. triangularis and S. Heeriana also 

 appeared somewhat pubescent, a fact which shows us again 

 that characters distinguishing the mature plant make their 

 appearance in the cotyledon, inasmuch as when mature these 

 are the most pubescent of the species here considered. 



