Germination and Groicth of Species of Salvia. 363 



The margins and under surface of many species were pro- 

 vided with minute, perhaps glandular, hairs, the purpose of 

 which is apparently to prevent the passage of water between 

 the expanding cotyledons, or to retain, as was actually 

 observed, a film of air between the delicate cells of the 

 young cotyledons and the moisture from the ground where 

 they had germinated. Such hairs were also found upon 

 the hypocotyls, and much more conspicuously and invariably 

 upon the petioles of the cotyledons, where they often 

 attained to a very considerable size. Their occurrence upon 

 the petioles must assuredly be regarded in the light of a 

 protection for the young leaves of the plumule, over which 

 they met when the petioles were nearly approximated in the 

 youngest stages of plumular development. In S. lyrata these 

 hairs gave a markedly hirsute appearance to the petioles, 

 although the lamina was ordinarily smooth. 



As to the development of the petioles, we may further 

 remark that the length of these in the gTeater number of 

 instances did not exceed that of the laminae. A glance at 

 the foregoing table will show that they do not often exceed 

 the lengtli of the lamina. They commence to gi'ow only 

 after the laminse have been visible for a considerable time, 

 and, we presume, may vary very much in length, accord- 

 ing as they are exposed to a greater or less amount of 

 light. 



In some cases a great difference was to be observed in the 

 lengths of the two petioles in one individual, phenomena 

 generally, but not always, to be accounted for by the position 

 in which the seedling was growing. As a rule, the petioles 

 are stout rather than attenuate. They attain their greatest 

 length in those species in which the subsequent leaves have 

 the longest petioles. 



The growth of the hypocotyl is hardly evident in any of 

 the species we have here considered. As will be observed 

 later, the general habit of the greater number of these species 

 is an appressed one, hence it is of S. Hceriana only that we 

 have any note upon the development of the hypocotyl. Of 

 this species, on the 7oth day after germination we have 

 noted, a " distinctive feature is, that whilst the seedlings are 

 not crowded together, nor in a position where they are liable 

 to be ' drawn up,' they have longer hypocotyls than any of 



