152 
Hans Hallier. 
centre of Borneo 1 I had an excellent opportunity of examining 
representatives of nearly all the natural orders of Flowering Plants 
under natural conditions. The academical lectures of Professor 
Ernst Stahl, as well as the personal influence of this suggestive 
botanist and of Professor Jean Massart, my enthusiastic companion 
in many excursions in the vicinity of Buitenzorg 2 , induced me to 
apply to systematic botany, the results of plant-ecology and mor¬ 
phogeny. As a result of these various influences 1 reached the 
conviction that there can exist only one really natural system, 
namely that which is identical with the tree of descent; to recon¬ 
struct this, systematic botany should be founded on a much broader 
and more universal base than at present, comprehending not only 
the morphology of the reproductive organs, but also all the other 
branches of botany, such as comparative morphology of the 
vegetative organs ; comparative anatomy, ontogeny and embry¬ 
ology ; phytochemistry, physiology and ecology ; structure of pollen 
and seed coat; relations to climate, seasons and to the surrounding 
organic world ; plant geography ; palaeo-phytology, etc. 
Thus since the elaboration of my first botanical publication 
(in 1890-2) till now I have always paid special attention to these 
points in reference to natural affinity. The results of these 
comparative studies have been published in a series of papers, most 
of which refer not to the whole system of flowering plants, but 
to single orders or alliances. It was only on my second voyage to 
the tropics, that I felt impelled to publish, in April 1903, a 
provisional account of my system as a whole. At that time I had 
to take into account the possibility that the Tagal people might 
not let me out of the Phillipine Islands, or that a typhoon 
might throw me into a shark’s mouth or into the depths of the 
South Sea, and I therefore thought it wise to publish my system at 
once, incomplete as it was. Moreover I hoped, that during my 
absence competent botanists would have time and leisure to 
digest my new system and to subject it to discussion, but in this 
latter point I am somewhat disappointed. Hitherto reviews on 
my system have been few in number and several of them very 
diffident or even unfavourable. The more favourable ones are the 
following. 
1 The results of the botanical explorations of this expedition have 
been described in the Natuurkundig Tijdschrift voor Neder- 
landsch Indie LIV. (1895) pp. 406-449 and in the Naturwissen- 
schaftliche Wochensclirift, XI. (Berlin 1896). 
2 See his interesting descriptions of these trips in his paper, 
Un botaniste en Malaisie, published in the Bulletin de la Societe 
royale de botanique de Belgique, XXXIV. (1895), part 1. 
