482 GEOLOGICAL SURVEY OF THE TERRITORIES. 
saes and the posterior branchial lobes of the domesticated mature speci- 
mens of both vessels, measuring also the length of the body, finding also 
the ratio between the length and width of these appendages to the length ~ 
of the body, inclusive of the furca. ‘The resulting figures gradually in- 
creased with the strength of concentration of the salt water in one or 
the other vessel in two different directions, the animals showing in the 
fourth week of domestication a very considerable difference, which 
plainly illustrated the increase of the length, and more so of the width, of 
said appendages at a heightened density of the salt water, and also the de- 
crease of those parts at a reduction of density of the water. Toward the 
end of the fourth week the salt water in both jars attained a difference of 
10° Beaumé, the gradually-diluted salt water showing then 3° Beaumé; 
the salt water of gradually-increased density indicated 13° Beaumé. 
To compare the size of the gill-sacs and posterior branchial lobes of Ar- 
temia salina at decreasing and increasing density of the salt water, in 
measuring I searched for figures which indicated which part of the body- 
length the length and width of these or those appendages in these or 
those specimens formed. During the fourth week of the above-men- 
tioned period of domestication I obtained the following figures as aver- 
age results in two diverging directions: 
At a decreased density At an increased density 
of the salt water 
the gill-sacs yielded 
in length the 24, 3, . in length the 22, 4, 
in width the 46, 5 in width the 40, 6 
part of the entire body-length; 
the posterior branchial lobes yielded 
in length the 17, 6, in length the 16, 8, 
in width the 38, 9 in width the 34, 9 
part of the entire body-length. 
I have to remark that toward the end of the period of domestication 
the resulting figures in the measurements showed considerable oscilla- 
tions. The cause of it is that in salt water of extremely decreased or 
-extremely increased density the animals soon became so short-lived 
that the older individuals, as well as the younger just before or soon 
after becoming sexually mature, died. The relation of the body-parts 
in such young, though sexually mature individuals, resembles in some 
degree the relation of the body-parts in young immature individuals 
in another surrounding element, then normal for the species; for we 
observe also a slight retardation of growth in a suddenly produced ex- 
treme decrease of the density of the salt water the same as in the in- 
crease of the density of the salt water. In insufficiently gradually 
diluting the salt water the individuals of Artemia salina die, as it were, 
of debility, which cause lies probably in the heightened oxidation in the 
organism dependent on the increased quantity of air in diluted salt 
water. The highest development of the furca and the greatest number 
of its bristles are not incongruous with the lowest density of the salt 
water which this species can endure for a longer or shorter time, but it 
is congruous with a concentration not much lower than that peculiar to 
the species. The more gradual the concentration of the salt water ir 
the domestication of successive generations of Artemia salina is changed 
the more deviates the mean (for this species) favorable concentration 
from that concentration which is the mean for it in free nature. 
In comparing Artemia salina with those degraded forms and genera 
of this species exhibiting the characters of Artemia milhausenw, living 
