Cockayne. — Ecological Studies in Evolution . 19 



Canterbury College for six years and kept its habit, but later on it too com- 

 menced to put forth erect shoots. 



2. Coprosma Baueri Endl. when growing on a sea-cliff is a straggling 

 shrub, more or less closely flattened to the rock-surface, and puts forth 

 nothing but long spreading horizontal shoots. Such plants bear flowers 

 and fruit. This growth-form of the species may be referred to wind, and 

 perhaps heat. But when C. Baueri grows in a coastal forest, or even when 

 isolated on loamy clay, it is a tree with a stout trunk. Plants which I raised 

 from seed, and which are now growing in the experiment-ground at Canter- 

 bury College, possess long spreading horizontal shoots— i.e., they are of 

 the shrub form, as above; but they are also developing erect shoots, and, 

 if permitted, they will eventually grow into trees (see Plate II, fig 2). Here 

 it is possible that the prostrate form is inherited from the race of rock- 

 frequenting plants. But the stimulus has not been sufficient to make a 

 really permanent race, and so the prostrate form only occurs during an 

 early stage in the ontogeny of the individual. Similar cases of partial 

 heredity are dealt with further on when treating of prolonged juvenile 

 forms. 



3. Olearia Lyallii Hook. f. (Compos.) forms a pure forest on some of 

 the New Zealand subantarctic isknds. A striking feature is the prostrate 

 or semi-prostrate trunk, which may be referred to wind, a peat soil, and 

 perhaps a uniform low temperature. In the interior of the forest, no 

 matter how boisterous is the wind without, it is quite calm, and yet the 

 seedlings are nearly always more or less prostrate at first. So, too, with 

 the seedlings of 0. Colensoi Hook. f. when growing on the mountains of 

 Stewart Island. 



4. The case of Sophora microphylla Ait. and S. prostrata Buchanan : 

 This is fully discussed in this paper under the heading " Persistent Juvenile 

 Forms " (p. 25), to which it may be well perhaps for the reader to turn 

 and consider the case in relation to the point under discussion. 



It would be beyond the scope of this paper to mention in detail instances 

 of after-effect of stimuli in places other than New Zealand, but it is well 

 to briefly enumerate a few of the more striking. Such are Schiibler's 

 cereals, which, grown in a northern climate, ripened their seeds earlier even 

 when cultivated in southern countries ; Cieslar's conifers, whose seeds, 

 collected in the Alps, when sown on the plains produced plants of slow 

 growth and small diameter ; Klebs's Veronica and Sempervivum, whose 

 striking abnormalities of inflorescence were repeated in plants raised from 

 seed ; Blaringhem's races of maize and barley originating from plants pur- 

 posely damaged in a specific manner (Blaringhem, 1907) ; Zederbauer's 

 experience with a form of Capsella Bursa-pastoris from an altitude of 

 2,000-2,400 m. in Asia Minor, which through four generations in Vienna 

 maintained in part the special alpine stamp ; and MacDougal's ovarial 

 treatments, where one new induced form has maintained its character, so 

 far, up to the fifth generation (see MacDougal. 1911, pp. 56, 57). 



5. Convergent Epharmony. 



From what has gone before, it is plain that various growth-forms of 

 New Zealand plants may be referred with confidence to stimuli from outer 

 factors. It has been seen also that of such forms some are merely environ- 

 mental; but there are others, now to be dealt with, which are hereditary, 

 and remain constant, unless perhaps when exposed to such a change of 

 conditions as they would not encounter in nature. 



