364 Mr Philip Sewell's Observations upon the 



the species in which 'a drawn' condition is not evident." 

 Even in S. Heeriana the hypocotyl was only 11 mm. long. 

 The great development of internodes which, at an early stage 

 characterises this species among those which have germinated 

 successfully, is sufficient explanation of the presence of the 

 hypocotyl. 



The Development of the Plumule. 



The plumule in all the species of Salvia which we have 

 examined is exceedingly small when the cotyledons expand 

 above the surface of the soil. In 8. Forskohlei and S. Tenorii, 

 for instance, it could not be seen without the removal of a 

 petiole and cotyledon, nor did it exceed 0'5 mm. until a few 

 days after the cotyledons had emerged. 



In the above-mentioned species it was not until the 

 16th day after the seed had germinated that the first 

 two leaves of the young plant could be seen distinctly. 

 Sixteen days later, in these two instances, the extreme 

 measurement from tip to tip of these first leaves was 

 only 4 mm. But the growth of the plumule in many 

 species which germinated later was much more accelerated 

 by the, we presume, more favourable conditions of tempera- 

 ture under glass. Nevertheless, among species which de- 

 veloped at the same time — e.g., the two species we have 

 instanced and S. canariensis — there was observable a very 

 different rate of growth under the same conditions. By the 

 30th day the plumule of S. eanaricnsis was more than twice 

 the size it was in the other two species. At a later stage 

 the mature leaves were much longer in this species. The 

 growth of S. triangularis may be instanced, in which there 

 was produced a first pair of leaves of the same size as 

 those of S. ceratophylla, in half the time taken by the latter. 

 In this case, however, the subsequent development was 

 different, inasmuch as S. eeratophglla rushed ahead very 

 quickly. 



The sizes attained by the first leaves seemed to have no 

 relation, either when mature or at the earlier period of their 

 growth, to the sizes attained by the cotyledons. 



Instances of this were frequent, where individuals of one 

 species, with smaller cotyledons, would possess larger first 



