490 GEOLOGICAL SURVEY OF THE TERRITORIES. 
prosper in such non-diluted salt water, which was taken from the salt 
lake at a middle concentration peculiar for this species (Artemia salina), 
but they do not prosper so well in a narrower jar with higher water-sur- 
face, as they soon die in such a water. In the same narrow vessel and 
at the same high water-level these animals will still prosper if the salt 
water is proportionally diluted. In this latter case the animals are so 
- circumstanced, as in more saline water in the broader jar.with lower 
water-level. The diluted water contains more air, it being more pene- 
trable and better adapted for gas exchanges. 
5. Accepting the fact that the water in a salt lake at a given time 
shows 10° Beaumé, and that it is populated with crustaceans of the 
genus Artemia, if we now take two equal vessels, placing in one of them 
water of this salt lake and a certain number of specimens of one genus of 
these crustaceans, and placing in the other jar specimens of the same 
animals out of the same salt lake, diluting the salt water to 7° or 6° 
Beaumé, a large number of animals will die in the first vessel under 
the same conditions, while keeping up the initial concentration of the 
water, but in the second vessel the majority of the animals will remain 
alive. In the second ease, that quantity of air is as if restored, which 
is wanting in the first, apparently by the influence of the vessel itself, 
as the water in the vessel is under different conditions from that in the 
salt lake. ‘This is all the more so the case with a summer-like tempera- 
ture. 
6. The animals prosper also in a non-diluted ‘salt water better at a 
temperature lowered to a certain degree than at a higher temperature, 
yet they do much better in diluted salt water, when the concentration 
of the salt water has not been reduced above a certain degree. 
7. Finally, the enlargement of the surface of the gill-sacs in Artemia 
with the increase of concentration of the salt water proves, as mentioned 
already above, apparently the dependence of Artemia in this relation 
principally on the reduction of air-capacity of such a water, even if the 
gill-sacs, accordiug to their location and formation, as it were, in these 
animals represent modified organs of locomotion. It remains for the 
physicists to determine how considerable is the solubility (the coefficient 
of assumption or of capacity) of the oxygen of the air in salt water when 
the variation of its concentration varies. In relation to this I can find no 
accurate data. 
II].—THE GENERA ARTEMIA AND BRANCHIPUS, AND THE RELATION 
OF SOME OF THEIR SPECIES TO THE SURROUNDING ELEMENTS. 
In the whole order of Phyllopoda the species of the genera Artemia 
and Branchipus are apparently those which are most sensitive to the 
influence of the surrounding element, in such a sense that a modifica- 
tion of the surrounding element is capable of producing in their genera- 
tions in a pretty short time visible mutations in their forms. A change 
of the surrounding element can even in one and the same generation 
produce such a variation of some parts of the body that it is difficult, 
in a State of nature, to immediately distinguish those forms which are 
most closely allied to each other. The species of these genera have 
been found by me mostly in salt lakes and salt ditches (Artemia exclu- 
sively), whereby they distribute themselves in such a manner that each 
species is peculiar to a certain concentration, and the change of this con-: 
centration in artificially domesticating their generations produces a 
change of form in the direction towards the next species or race which 
lives in another concentration of salt water, toward which side the 
