86 K. H. CAMBAGE. 



my own garden, seedlings of Acacia falcata appear every 

 year, and these are from seeds which have been in the soil 

 for twenty-six years and upwards. 



Hypocotyl. 



The hypocotyl varies in colour, thickness and length. So 

 far as observed, it is usually glabrous in this genus, but in 

 some species the upper portion may in time become 

 sprinkled with a few hairs, and it tapers from base to apex, 

 generally evenly, but in some cases becoming suddenly con- 

 stricted just above the soil. Its colour ranges from very 

 pale or almost colourless, to pale green and pale pink, 

 brown or red. Its thickness at the base is from about 1 mm. 

 to 2 mm., and at the apex from about '5 mm. to 1*5 mm. 

 According to present observations its length ranges from 

 about 1 cm. to 5*5 cm., but the total length or extent above 

 the soil, does not appear to be constant for any species, 

 and is largely regulated by the presence or absence of 

 shelter, those growing in the open often being shorter than 

 others which are sheltered, and which attain the greater 

 length in their upward search for the light. The first por- 

 tion of the plant to appear above the soil is the curved 

 upper part of the hypocotyl and the base of the cotyledons. 



Cotyledons. 

 The majority of Acacia cotyledons are oblong with the 

 apex rounded, and with the outer side at first more or less 

 convex, and the inner surface flat. Some are ovate while 

 others are orbicular. All, so far examined, have entire 

 margins but may be sagittate or auricled at the base, and 

 are glabrous. The majority are sessile though a few are 

 distinctly petiolate. As the curved upper portion of the 

 hypocotyl straightens out it gradually pulls the cotyledons 

 from the soil and out of the testa, the apex being the last 

 to appear. If the seeds are not sufficiently covered with 

 soil, they sometimes appear before the cotyledons have 



