Cockayne. — Development of Seedlings. 267 



taken for a distinct species ; and yet the individual of the forest 

 and the one of the open might have been actually produced 

 from seed not only from the same parent, but even from the 

 same capsule. It is very difficult to estimate what part is 

 here played by environment and what by heredity ; at any 

 rate, it seems to me that so long as the forest should present 

 the same conditions, then so long would P. rigidum keep 

 the juvenile form. And, further, were the xerophytic condi- 

 tions absent, which state of affairs a change in climate could 

 bring about, tben the xerophilous form — i.e., the common 

 form of the plant — would cease to be produced, though there 

 seems no doubt that this form is hereditary, and thus the 

 juvenile form, resembling most likely in many respects the 

 ancestral form of the plant, be the sole survivor. On the 

 other hand, a change of climate might banish the forests, and 

 allow only the xerophilous form to exist.* 



No. 783. Stellaria roughii, Hook. f. Plate X., fig. 4. 



The seed was collected on the 3rd April, 1899, from one 

 individual growing on a shingle-slip on the Mount Torlesse 

 Range, at an altitude of 1,000 m. It was sown on the 

 9th September, 1899, and began to germinate on the 11th 

 November, 1899, the germination continuing at intervals un- 

 til June, 1900. 



Description of Seedling. 



Root very long and of very rapid growth ; in a plant with 

 the hypocotyl just visible above the soil it is 10-5 mm. long, 

 and in a plant 55 mm. tall it is 31 mm. long; soft and suc- 

 culent at first, but soon becoming extremely flexible ; pale in 

 colour, slightly wavy. 



Hypocotyl greenish even when underground, afterwards 

 pale-green, sometimes marked with brown on its upper por- 

 tion ; 4 mm. long before the cotyledons have emerged from the 

 soil, finally 6 mm. in height above the soil ; soft and succulent 

 at first, but soon becoming so elastic that when bent to the 

 ground it springs back into position ; rarely quite straight and 

 erect, often semiprostrate, terete, glabrous. 



Cotyledons continue increasing in size for some time after 

 they have opened out to the light, greenish even when under- 

 ground, becoming finally pale-green ; when fully grown 7 mm. 

 (including petiole) in length by 1-5 mm. in breadth, linear- 

 spathulate, obtuse or rarely subacute, entire, glabrous ; peti- 

 oles equalling lamina in length, semiterete, swollen and 

 connate at the base. 



* This idea is worked out at greater length further on in this paper 

 when treating of the differences between Chatham Island seedlings and 

 those of the same species in New Zealand. 



