PACKARD. | TRANSFORMATION OF ARTEMIA. 503 
the former already at 20° Beaumé represent a just as far degraded or 
retrograded form as do the latter at 23° or 24° Beaumé, and that the 
former occur principally in one, but the latter in another, now cut-off 
part of the Kujalnitzki salt lake. For better distinction I shall call the 
former the smaller, the latter the larger form with the characters of A. 
milhausenit. 
Did this Artemia, with the characters of A. milhausenti, one form of 
A. salina, change by the influence of the surroundings, or one by the 
influence of the same in the development-retarded form? To this ques- 
tion the characters themselves, and the course of postembryonal devel- 
opment of this modified and also in development retarded form, answer. 
Not only characters show themselves in this form peculiar to the younger 
age of A.salina, and originated from retarded development, but. also 
newly acquired to the surrounding adapted characters. The young 
individuals of A. salina and its variety have, as is known, in the begin- 
ning no furca, but it develops much later. This circumstance testifies 
that in adults with the characters of A. milhausenit no furea has been 
formed, owing to retarded growth. But we must consider that in those 
transitory forms between A. salinaand A. milh., which in mature and old 
age have a little-developed furea, with a very small number of bristles, 
have, in still young age, just before the appearance of sexual maturity, 
and shortly after the saine, a still more developed furca, with a larger 
number of bristles preserved, than in old age, during which this part at 
one and the same salt capacity of the water more degrades. This phenom- 
enon can still be better noticed in the domestication of successive gen- 
erations of A. salina in salt water of gradually increased concentration, 
wherein that period, during which the furea mostly develops, shortens 
with each following generation, the development of the furca becoming 
a weaker one, appearing tn shorter tme-spaces. It is important that this 
period includes the space of time immediately before and partly algo 
after the appearance of sexual maturity, in the beginning of mature 
age; also in those specimens in nature in which in later, mature, and 
old age altogether no furea exists, a little developed appears in said 
period, partly with bristles, or only in later generations, by the influ- 
ence of the surroundings in the same direction, this phenomenon of char- 
acters of higher original form is more and more obliterated. All these 
phenomena prove that the absence of the furca in the forms with the 
characters of A. milhausenit depends upon retarded development of the 
organization of the generations, not only from the appearance of sexual 
maturity still before the full development of the body parts, but also 
from the immediate influence of the salt water of higher concentration, 
at which the appendages just beginning to develop became as if atro- 
phied. There are many similar examples of retrograde development of 
the form and of the individual. . 
The greater length and slenderness of the postabdomen in the speci- 
mens with the characters of A. milhauseniti compared with the part in 
minature and still more in younger A. salina, proves with certainty that 
the organization of such specimens in this relation depends almost entirely 
upon the immediate influence of the element, but not upon an indirect 
influence, 7. é., from the mechanical pressure of the salt water, and the 
later appearance of sexual maturity, and not from the retained growth 
and the appearance of sexual maturity before the complete development of 
the body-parts. Wad the postabdomen of the specimens with the char- 
acters of A. milhausenii formed as a consequence of retarded growth and 
in comparison to A. salina earlier and betore the full development of 
the body-parts ensuing appearance of sexual maturity, this postabdo- 
