308 ZOOLOGY. 
by students who are yet chiefly occupied with the cooperative la 
of natural selection. ; ee 
Acceleration and retardation of the period of reproduction 
may possibly have occurred ; but the only case in which it has been 
recognized in connection with the above law, has been int 
to sex. In the human species at least, differences in sever 
characters, mostly metaphysical, seen in the sexes and in certain 
races, may be consequences of the earlier or later appears 
maturity in this point. — Z. jas 
PARTHENOGENESIS AMONG LEPIDOPTERA.— The Dutch. na = 
M. H. Weizenbergh jr. has performed a series of experin 
this interesting subject, the insect placed under observation Ah 
Liparis dispar, and concludes that it is possible for at least t 
successive generations to be produced without access of the 
to the female. The following are the results of his very ® 
experiments: — (1) August, 1866, eggs laid by impre 
males; April, 1867, caterpillars appear, and in July perfect 
flies. (2) August, 1867, eggs laid by females of this yet i 
without impregnation; April, 1868, caterpillars appear: 
July perfect butterflies. (3) August, 1868, eggs laid b 
of this year without impregnation ; April, 1869 caterpil : 
and in July perfect butterflies. (4) August, 1869, eggs 
females of this year without impregnation ; April, 18 
the eggs all dried up. The power of reproduction ^p 
decrease year by year when impregnation was prevented. A 
results have been noticed in other butterflies, in bees, and 
in aphides.— A. W. B. eae 
can brook 
M: 
NATURALIZATION OF SALMONIDÆ. — The Ameri 
Salmo fontinalis, is now thoroughly established in £n 
it is the admiration of pisciculturists. io “ 
There seems to be no question about the success of T 
to introduce the European trout, S. fario, into the ps 
and Plenty in Tasmania, good-sized fish of that species in” 
casionally caught there. As to salmon (5. saari T 
trout (S. trutta), the evidence of success is not ao = 
letter from Tasmania, dated Dec. 30, 1871, and pub! 
and Water,” asserts that there is no doubt that the 
coming yearly, more and more fully stocked vib 
that no adult salmon have been caught. James A. . = 
