THE BOTANY OF THE KACHIN HILLS NORTH-EAST OF MYITKYINA. 309 
chinensiSf that are peculiarly Chinese. The meagreness of the 
Chinese element is emphasised by the fact that in Malaya, with th** 
whole of Indo-China intervening, and in India with Assam interven- 
ing, we find respectively 228, or 36*36 per cent., and 218 or 34*76 
per cent., of our Kachin Hill plants. 
In Eastern Indo-China we find almost twice as many Kachin 
Hill plants as we do in China, the number and percentage being 
402 and 64*1 1 , respectively. The especially Indo-Chinese element 
is seven times as great, for there are twenty-one Kachin plants that 
occur, out of Kachin, only on the Shan Plateau or in Prome, Tonquin^ 
and Siam. Still the number of Kachin Hill species in Eastern Indo- 
China is exceeded by the number that occur in the Eastern Hima- 
laya, whither 416, or 66*34 per cent, of our plants extend. The pe- 
culiarly Himalayan element is, however, only about one-third the 
strength of the Shan element, for there are but eight Kachin species 
peculiar to the Himalaya, as against the twenty-one peculiar to the 
country east of the Irrawaday. If, however, we think of the species 
that extend from the Kachin Hills, both to the Himalayas and to 
the Assam ranges, without occurring in Eastern Indo-China at all, 
we are able to realize how small the Shan element really is. There 
are as many as 67 species, io*68 per cent., of the flora, that belong 
to this category, more than thrice the number that are peculiarly 
Indo-Chinese. The affinities of the Kachin flora are thus manifestly 
greatest with the floras that characterise the Himalayan and Assam- 
Arracan siib-sub-areas, particularly the latter, since 522 species, 
83*25 per cent., or about five-sixths of the whole list occur in the 
Assam Ranges, and as many as 46, or 7*03 per cent., of these species 
are peculiarly Assamese. The Mishmi-Kachin block then, so far at 
least as the evidence derived from the present collection in its 
Eastern or Kachin section goes, must be treated as part of the 
Assam-Arracan sub-sub-area rather than as a part of the Chinese, 
the Indo-Chinese, or even the Himalayan regions. 
The comparative value of the influences exerted oy the four 
adjacent areas of China, the Eastern Himalaya, Indo-China east of 
the Irrawaday Valley, and the Assam-Arracan ranges, are however 
more accurately determined by employing in succession the numbers 
indicated by each actual distributional arrangement that occurs. By 
treating the figures thus attained as numerators and by using as 
denominators the number of adjacent areas involved in each case, 
we obtain a series of fractions the sum of which gives us a number 
that indicates the proportional influence of each adjacent ai*ea in the 
