AUGUST 27, 1897. ] 
bands become spots and combine into a 
transverse marking by the agency of dark 
colored scales on the transverse veins. If 
we neglect secondary differences of mark- 
ings in the two groups of Papilio, we have 
to assume that they originated in complete 
independence of each other—a direct rela- 
tionship cannot be proved—according to 
the same definite laws of development. 
In entire groups as well as in single spe- 
cies, no matter whether they live in the 
same or in different districts, the law of a 
definite direction of evolution is shown in 
homogenesis, or independent similarity of 
evolution. As examples, Eimer cites the 
North American Twrnus and the south Eu- 
ropean Alexanor (which is also found in 
Asia Minor), of Segelfalter the South Ameri- 
ean Agesilaus, Protesilaus and the European 
Podalirius. 
The phenomenon of homogenesis is of 
importance asa proof that it is not geo- 
graphical distribution in the sense of local 
separation on which the development of dif- 
ferent directions-of evolution depends. 
This short exposition of the direction of 
evolution in the genus Papilio seems to me 
to show that it was not arbitrariness on 
Eimer’s part to select Papilio Podalirius as 
the ancestral form of his group of butter- 
flies. He has shown, by his study of the 
markings of one series of forms, that those 
of all its members can be reduced to one 
and the same scheme, and that aberrations 
from the forms which are nearest to this 
original scheme of markings vary so as to 
form transitions to nearly allied species, 
which again are connected with more dis- 
tant species, and the conclusions drawn 
from the study of these phenomena are con- 
firmed by the results of geographical distri- 
bution. This being so, I cannot under- 
stand how Minot can doubt that Himer’s 
assertions are correct. 
Neither does Minot agree with the ex- 
planation of the sudden appearance of a 
SCIENCE. 
dll 
second perfectly dark-colored form of the 
feminine Papilio Turnus by ‘development 
by jumps’ (Halmatogenesis). This singu- 
lar form of feminine Yurnus called var. 
Glaucus, which occurs exceptionally in 
the North and regularly as a summer gen- 
eration in the South of the United States, 
seems not to be connected by any transi- 
tions with the normal feminine animal. 
Minot, however, believes it possible that 
in former times transitional forms existed. 
It seems to me a matter of course that a 
highly developed form like Papilio Turnus 
var. Glaucus has to undergo several varia- 
tions of markings during the chrysalis 
stage before it can leave it in its present 
form. Butin comparison with the differ- 
ence between the variation of another spe- 
cies and its original form, that between 
Turnus and var. Glaucus remains just as 
striking, whether we know that during the 
chrysalis stage forms of transition tempo- 
rarily occur or that in former times forms 
existed which made the transition from the 
normal feminine Turnus to the var. Glaucus 
somewhat more gradual. As it at present 
appears, var. Glaucus is a form produced 
by Halmatogenesis. Eimer’s theory neces- 
sarily leads to the conviction that qualities 
produced by external influences are trans- 
mitted to the descendants of those who have 
acquired them, an assumption for which 
Minot demands proofs. The experiments of 
Weismann on Polyommatus phleas, which are 
mentioned in the Zoologische Jahrbiicher, 1895, 
Abteilung fiir Systematik, show that this 
transmission of qualities from their posses- 
sor to his descendants really occurs. 
It is by no means every individual that 
undergoes a change through the influence 
of unaccustomed external influences. Sev- 
eral preserve the parental aspect. And as 
the parental characteristics were not from 
the beginning such as they are at present, 
but are, as is shown by experiment, the re- 
sult of certain conditions, the transmission 
