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MR. W. BATESON ON SOME VARIATIONS OF CARDIUM EDULE 
Aral shells have been living for ages in water containing less than a third of the salt 
contained in Mediterranean water, and the Aral Cockle is quite sufficiently different 
from that of the Mediterranean to constitute a well marked variety. So that, while 
the Cockles originally isolated in Abu Kir came directly from the Mediterranean, the 
ancestors of those which were subjected to increased saltness at Jaksi Klich, &c., had 
been living in brackish water in the Aral Sea for an indefinite number of generations, 
yet the resulting forms in both cases are closely alike. 
It is not well to press conclusions of this kind too far, and it may be that unfavour¬ 
able conditions of some kind quite other than increased saltness may result in 
producing similar variations. All that can be stated with certainty is that shells 
exposed to increasingly salt water do change in a particular way, and that they do so 
with great regularity and uniformity. In the same way it has been shown that the 
influence of fresh water does not lead to the production of a peculiar type of shell. 
In the case of the variation consisting in increased proportion as to length, it is e.spe 
daily probable that the cause lies in the general unfavourableness of the conditions. 
It was shown to be present both in those shells which had been exposed to salt water 
and in a still greater degree among those which had been living in fresh water. It is 
not rare to find occasionally shells of Cockles from the English coast of similar shape. 
Nevertheless, the regularity of the presence of this feature among the shells from 
these abnormal situations is so great as to make it certain that this phenomenon is in 
some manner due to the conditions. Instances in which it is possible to actually 
trace the occurrence of variations are so rare that no apology is required for having- 
given so much attention to details which would be otherwise unimportant. In the 
cases here given it has not only been possible to observe the variations, but also to 
obtain the actual ancestors of the varying offspring for comparison, and in the case of 
the shells of Shumish Kul an opportunity is given of doing this at several successive 
stages. 
I wish to express my thanks to many persons who have assisted me in the course 
of my investigations and especially to Sir Kobert Morier, G.C.B., British Ambassador 
at St. Petersburgh, who obtained permission for me to travel in Central Asia; to 
M. Semenow, Vice-President of the Imperial Geographical Society, and to M. 
Maximovitch of the Botanic Garden, for much valuable information and advice ; also 
to C. A. CooKSON, Esq., C.B., British Consul at Alexandria. Moreover, though this 
page may never reach them, I cannot let this opportunity pass without expressing my 
gratitude for the courtesy and hospitality which I everywhere met with at the hands 
of the Kirghiz people. 
