1915-16.] BOTANICAL SOCIETY OF EDINBURGH 4-7 



might show variation only to the extent of subsectional 

 value, and that onlj^ towards the extreme ends of the range. 

 Consequently with the coming of the break, and the sub- 

 sequent driving in towards the common centre of the 

 eastern and western floras, by the means indicated, these 

 varieties might be brought together at the break, and, 

 travelling southwards in company, give rise to a host of 

 new forms. 



It need scarcely be said, however, that if the Sino- 

 Himalayan range theory is to account for the broad 

 distribution of the Primulas in this part of Asia, it must 

 also to a large extent account for (i) any peculiarities of 

 distribution in the genus, both in Asia and elsewhere, .since 

 these three areas now constitute the great Primula area of 

 the world, accounting for about 80 per cent, of known 

 Primulas; (ii) for the distribution of other alpines in this 

 region ; and (iii) for the distribution of plants in the valleys 

 as well as on the ridges, and for the limits of meeting 

 floras, e.g., the Chinese and monsoon (Indo-Malayan). 



To take first the detailed distribution of one or two 

 sections which call for remark. The range of § Candelabra 

 is as follows. Two yellow-flowered species occur in the 

 Himalayas, and the section then expands as usual along 

 the Burma-Yunnan area, where we find three yellow- 

 flowered species (a fourth is known from Tatsienlu) and a 

 new colour group (purple) with five species ; the group 

 extends westwards into Burma, where P. Jtelodoxa, Balf. f., 

 and P. Beesiana, G. Forrest, are found, and southwards 

 into Java, where a single yellow-flowered species is found. 

 Now going east across the irruption area we find one 

 purple-flowered species in Eastern Szechwan — -but this 

 may belong to the Burma-Yunnan area — and two purple- 

 flowered species from the Far East, one Japanese and one 

 Formosan. Here it appears that the purple-flowered 

 species of the east and the yellow-flowered species of the 

 west have met in the irruption area and travelled south 

 in company, giving a fresh impetus to development in the 

 section. 



It may be pointed out here that nearly all the Bui'mese 

 Primulas known are really Yunnan Primulas. I myself 

 found more than a dozen species on the western slopes 



