PACKARD. ] TRANSFORMATION OF ARTEMIA. 479 
variety of Daphnia magna, the latter variety being itself again an inter 
mediate form between the typical Daphnia magna and D. pulex. If we 
would restore the middle radical form, which gave origin to Daphnia 
magna and D. pulex, we would receive a form most similar to our Daph- 
nia magna varietas, in the production of a still farther allied, a prototype 
for the largest number of Daphniz, we would arrive at a form most 
similar to Daphnia degenerata from the salt-water ditches. Such ex- 
amples show that, owing to the neighborhood of salt waters in which the 
generations of the fresh-water species distribute themselves and in 
which they change under retardation of development, the species them- 
selves in fresh waters of such districts deviate to a certain degree jrom the 
typical form, 1. e., they change toward the direction of the next lowest 
species of their genus. In consequence of the existence of such an ele- 
ment in these districts the area of distribution of the species changes; 
but as the center of this area will be found somewhere between the 
fresh-water and the salt-lake e‘ement, the aberration of the fresh-water 
generations in the neighborhood of salt-lake waters, in which the gene- 
rations of the fresh-waters pecies already considerably changed them- 
selves and become retarded in their development, is easily understood. 
The salt ditches, which distribute themselves on saline soil near Odessa 
between the sea and the two salt lakes, the Chadschibaisky and the Ku- 
jalnitzky, become fresh-water ditches after gradual elevation, and sim- 
ultaneously begin to become populated with fresh-water generations, 
whereby these generations form, to a certain degree, changeable transi- 
tions toward the more changed salt-lake forms. Some of the ditches six 
years ago containing salt water of about 5° to 4° Beaumé, and inhabited 
by the salt-water species, Branchipus spinosus Milne Hdw., now contain 
nearly fresh water, and are populated this year (1876) with the fresh- 
water forms Daphnia magna Leydig varietas and Cyclops brevicaudatus 
Claus, slightly changed in the direction toward the lower forms. In re- 
lation to the latter, a transitory form of Cyclops brevicaudatus varietas 
b' and Cyclops brevicaudatus Claus, was to me of great interest. In the 
real fresh-water Cyclops brevicaudatus the extreme inner one of the four 
farcal bristles is twice as long as the extreme outer, or actually the twenty- 
fifth part shorter than the double length of the last outer bristle; in gener- 
ations inhabiting less saline ditches the extreme inner bristle is, on an 
average, the sixth part shorter than the double length of the extreme 
outer. In Cyclops brevicaudatus varictas b. the extreme inner furcal 
bristle is but little (one-quarter) longer than the extreme outer. The 
adult forms of the changed generations of Cyclops brevicaudatus in the less 
salty ditches exhibit nearly the same relution of body parts, as seen in the 
young, immature, pure fresh-water forms of the same species ; but the ma- 
ture individuals of said variety correspond in this point with the younger 
individuals of the species:= 
To this I have to refer also the interesting influence of the surround- 
ings upon the development of specimens of Artemia. The growth of 
the specimens of Artemia salina in salt water of high density and at the 
same temperature proceeds at least twice as slow as the growth of speci- 
mens of Branchipus ferox in less saline water. Abstractedly from the 
fact that the growth of specimens of Artemia salina requires much 
time, sexual maturity appears much earlier in proportion to the full de- 
velopment of body-paris, than in Branchipus. At a high concentration 
‘Consult my paper in the “Schriiten” of the Neoruss. Soc. of Naturalists, vol. iii. 
part 2, pp. 32 to-36, and 74 to 77. Also on the domestication of Cyclopidi, ibiden, 
pp. 84 to 95. 
