Cockayne. — Development of Seedlings. 277 



Islands was pointed out to me about a year ago by Mr. S. D. 

 Barker, in whose garden I had the pleasure of seeing some 

 seedling plants sent to him by Mrs. Chudleigh. Shortly after- 

 wards I received from Mr. F. A. D. Cox the fine collection of 

 young plants from which the above description was drawn up. 

 Thinking that possibly, in common with Pseudopanax cliat- 

 hamica* the Chatham Island form of Plagianthus betulinus, 

 and perhaps other plants which pass through three stages in 

 New Zealand proper, did not go through the three stages 

 described above in this paper through which P. betulinus 

 of New Zealand passes, I wrote to Mr. Cox for information 

 on this point, so important in the life-history of the plant. 

 The following is a copy of Mr. Cox's reply, under date of 

 the 6th October, 1900: "Plagianthus betulinus. — This cer- 

 tainly does not pass through the stages you have mentioned ; 

 as far as I have observed branches and twigs are always 

 upright, as in the mature form, and leaves always the same 

 shape ; the appearance you mention of apparently two distinct 

 plants in regard to foliage, &o., is absent. Sophora tetraptera 

 never alters its form ; tiny seedlings have the leaves (of course, 

 in a smaller form) identically the same as in the mature tree ; 

 the only Chatham Island plant that has two distinct forms of 

 leaves — broad and narrow — on the same plant is Dracophyllum 

 scoparium."i 



If what Mr. Cox states is correct — and it is most unlikely 

 that so accurate and keen an observer can be mistaken — then 

 the question opened up as to the reason of this great differ- 

 ence in the life-history of a certain species according as it 

 is indigenous to New Zealand or to the Chatham Islands is 

 one of the greatest interest, but at the same time of the 

 most extreme difficulty. The theory which I am about briefly 

 to outline as an explanation of this phenomenon is the merest 

 hypothesis, and put forward chiefly as a basis on which in- 

 quiries can be made, not iu botany alone, but also in geology 

 aud zoology, so that, whether the theory be eventually sus- 

 tained or shown to be false, its examination may lead to the 

 publication of facts of considerable scientific importance. 



According to the principles laid down in Part I. J of this 

 series of papers, "a plant repeats in its ontogeny its phylo- 

 genetic development "§ more or less, and the later in the 



* Cockayne, Trans. N.Z. Inst., vol. xxxii., 1899, p. 89; and Kirk, 

 "" Student's Flora," p. 223. 



f In what follows the heterophyllism of D. scoparium need not be 

 taken ioto account, for I think it can be explained on quite local grounds, 

 which it would be out of place to enter into here. 



J I.e., p. 356. 



§ Ssrasburger, " A Text-book of Botauy," London and New York, 

 1898, p. 46. 



