Section D ^^r^>^- 



BIOLOGY 



ADDRESS BY THE PRESIDENT: 



F. M. BAILEY, F.L.S. 



Government Botanist, Brisbane. 





[The text of the address was not available at the time of going 

 to press.] 



PAPERS READ IN SECTION D. 



I —SOME EXAMPLES OF PRECOCIOUS BLOOMING IN HETERO- 

 BLASTIC SPECIES OF NEW ZEALAND PLANTS. 



By L. COCKAYNE, Ph.D., F.L.S. 



The flovvering of plants at an earlier stage of development than 

 the so-called " normal " is, as Diels^ has very clearly shown, a 

 matter demanding close investigation. Of especial interest is the 

 early blooming of strongly heteroblastic species, i.e., those whose 

 juvenile form is markedly different to that of the adult, particulai'ly 

 when the former stage of development is prolonged for a number 

 of years. 



Although a good deal is now known regarding the occurrence 

 of heteroblasty in New Zealand plants, the information is much 

 scattered, while but little has been pubUshed as to the blooming of 

 the juvenile stage. It seems well then to bring together some of 

 the leading cases of this latter phenomenon, so that they may be 

 at the disposal of students of evolution. 



Two aspects of the subject under consideration present them- 

 selves : — 1. The juvenile and adult forms are present at the same 

 time on the one individual — the juvenile below and the adult above, 

 or the former as reversion-shoots, perhaps in any part of the 

 adult. 2. The adult stage is altogether suppressed in some in- 

 dividuals. This last-named series is evidently the more important, 

 since if such a juvenile form flowers, it is to all intents and purposes 

 a distinct species from the adult, and would be so considered by any 



I. " Jugendformen und Blutenrtife im Ptlanzenreich." li)0(i. See also Goebel, " Organography,'*" 

 Part 1, pp. 145-UB and 153-155. 



