46 PRELIMINARY INQUIRIES. 



There is, however, another feature in the distribution of vegetation in North America, which has 

 been used as an argument in favour of the miocene Atlantis without regard to the interruption of 

 phenomena which must have been occasioned by the glacial epoch ; but which, if it was worth 

 anything as an argument when no such interruption was thought of, shoidd be equally good for an 

 Atlantis after it ; and that is, that the number of the species of plants which occur in Eastern 

 Asia diminishes as we proceed westwards. Mr. M'Clelland makes an observation to a similar 

 effect as regards the animals of Assam ; his catalogue of them displaying an interesting balance 

 numerically in favour of the extension of species from the eastward.* As to plants, out of 1550, 

 which is the number of Japanese phaenogamous species known up to this time. Dr. Gray has pointed 

 out that, supposing them to have been spread in the direction and from the point specified, by 

 the time they reach Europe they are reduced to 157 ; by the time they come to Eastern North 

 America they only nmnber 134 ; and when they get so far as Western North America we find only 

 120 species. 



The inference from this, of course, is that there was a highway open to the plants all the way 

 round the world from Japan to California ; and that as they got further and further on their 

 journey, species kept dropping off until, when they reached its end, only 120 species remained out 

 of 1550. The idea is plausible at first sight, but a little consideration will serve to show that 

 the distribution of species in North America has in reaKty nothing to do with that in Europe and 

 Asia, but that they are the results of two totally different trains of action. It is plain that if they 

 were part of the same train of action, they must bear a relative proportion to each otlier. If 1550 

 species are reduced to 157 ia journeying to Europe — say 7000 miles — they ought to have suffered a 

 further proportionate decrease by the time they have reached America, and a stiU greater by the 

 time they have reached California. Does that rate correspond with the results above given ? Here 

 they are compared : — 



LOSS PROPORTIONATE 

 ACTUAL LOSS OUT OF 1550. TO THE DISTANCES. 



From Japan to Central Europe, say 7000 miles — 1393=one in every five miles . 1393 



From Central Europe to Newfoundland, 3000 miles, 23 600 



From Newfoundland to California, . 4000 miles, 13 800 



In other words, according to that ratio the whole shoidd have been extinguished before they 

 had well left Em-ope ; the 157 left would not suffice to carry them across the Atlantic, even starting 

 from the west coast of Ireland. In the first 7000 miles, the missing amounted to 1363, in the 

 second only to 36 ; a result too extravagant to be seriously looked at, and yet not even so bad as 

 it really should be, because no allowance has been made for the increased ratio of loss which 

 we should expect to be consequent on increased distance from home. 



The real cause of the similarity of the floras of Eastern Asia and America is probably that 

 both started from a similar basis. In the miocene time one flora inhabited Europe, Asia, and 

 America. The glacial cold all but destroyed it in Europe, but in North America it found a refuge 

 in the south-west, and in Asia the distribution of land and water shows that its refuge there 

 must have been mainly in the south-east — not in the Malayan south-east, which was cut off" 

 from Northern Asia — but in the south-east of Northern Asia; in other words, Japan and the 

 north of China. The floras preserved in Asia and America would, of course, imdcrgo different 



* M'Clelland, Catalogue of Animals in Assam iu " Annals of Natural History." 



