1883.] Recent Literature. 1045 
will not prove that external changes in the environment and 
heredity, are not the two fundamental factors in the origin of life- 
forms; natural and sexual selection playing a subordinate rôle, 
and rather preserving forms already originated than bringing 
about new bivlogical creations. 
The second part opens with a discussion of the origin of the 
markings of caterpillars, based on a knowledge of the early 
stages of the Sphingida, which the author's industry has almost 
alone furnished. His results certainly seem correct, and we think 
analogous though far less numerous facts rae am, Sc. groups 
of caterpillars, as well as saw-flies larva, which we have 
will confirm Weismann's views. His evidence shows that there 
were once Sphinx larva without any markings, but with a caudal 
horn, as such a species now exists in the Berlin Museum. 
characteristic caudal horn is older than existing markings, All 
the data go to show that of the three kinds of markings, é z., longi- 
tudinal and obiique stripes and spots, the first are the oldest, and of 
the longitudinal stripes the sub-dorsal originated before the dor- 
sal and spiracular. The question as to the relative ages of the 
oblique lines and the spots does not admit of a general answer. 
The lines and spots are believed to have originated by the known 
factors of natural selection and “correlation” (Darwin), protec- 
tive mimicry here acting as one of the factors of natural selec- 
tion, the spots being of advantage to the larva. _ Sila 
The second section of this part is on phyletic nse to in 
metamorphic species. The author attempts to show that the 
section. Weismann here also is emphatic in stating that the ex- 
govt acne and induce 
_ ternal conditions of life produce the 
the organism to change. It seems to him “ incomprehensible 
__ Strongly, these transformations corresponding in extent with 
the organism is exposed in the two stages, to say nothing of the 
fact that by such unequal divergences the idea of a aei e sys- 
etely upset. , 
the author in the third part relative to the 
hosis of Siredon into Amblystoma are well known, as 
