AUGUST 27, 1897. ] 
showed by experiment—they let the chrysa- 
lids of the prorsa generation develop at 
low temperature, those of the levana at 
high temperature—that both butterflies be- 
long to one and the same species. Similar 
experiments have of late been made by 
Merrifield* and Standfuss{ and have re- 
vealed still more astonishing phenomena 
in a great number of butterflies. They all 
tend to prove that the forms developed in 
heat or in cold respectively, always possess 
those qualities which characterize varia- 
tions and nearly allied species of these but- 
terflies living exclusively in warmer or 
colder climates. And not only the mark- 
ings, but also the form of the wings and the 
whole configuration of the animal change. 
In his criticism Minot does not so much as 
mention these facts, which Himer regards 
as a proof that the views on which his 
theory is based are correct; on the contrary, 
he particularly emphasizes that Himer’s 
theories are founded only on the study of 
the markings of animals and the geograph- 
ical distribution of forms. It is true that, 
guided by the results of his earlier re- 
searches, Eimer regards these markings as 
the most characteristic signs of affinity be- 
tween the various species.{ And he con- 
siders as a further proof of the correctness 
of this assumption the results of the artifi- 
cial development of butterflies in lower or 
higher temperatures in their relation to the 
geographical connection of forms. 
*F. Merrifield: Transactions of the Entomolog. 
Soc. of London, 1893-94. 
{7 Standfuss: Uber die Griinde der Variation und 
Aberration des Falterstadiums bei den Schmetterling- 
en mit Ausblicken auf die Entstehung der Arten. 
Leipzig, 1894. The same: Handbuch fiir Sammler der 
europiischen Grosschmetterlinge. Ziirich, 1891. 
{ Darwin also came to the same conclusion, as he 
says: ‘‘ We shall hereafter see, especially in the chap- 
ter on Pigeons, that coloured marks are strongly in- 
herited and that they often aid us in discovering the 
primitive forms of our domestic races.’? Animalsand 
Plants under Domestication, Vol. I., p.29. London, 
1868. 
SCIENCE. 
309 
Eimer’s theory further materially differs 
from that of Natural Selection in its explana- 
tion of liabilities and tendencies to changes. 
Natural selection presupposes the most 
varied liabilities to changes, in order to be- 
come efficient in the production of forms; 
EHimer, on the contrary, is of opinion that 
individuals can only follow prior deter- 
mined, 7. e., definite tendencies of evolution 
(not predetermined tendencies, as Minot 
wrongly understands). This ‘Orthogenesis,’ 
in opposition to Nigeli’s view, does not al- 
ways tend towards perfection, but often to- 
wards simplification and retrogression. In 
its rudiments this law shows itself in the 
markings of animals, inasmuch as the primi- 
tive form of longitudinal stripes becomes 
spots, transverse stripes, and uniformity of 
color. This rule, which Minot wishes to be 
‘proved, not proclaimed ex cathedra,’ is fol- 
lowed, as is shown by Himer’s researches, by 
the ontogenesis and phylogenesis of rep- 
tiles,* birds,; and mammalia. Simroth{ 
found this law confirmed in Limaces, I my- 
self in the markings on the shells of marine 
gastropods.§ Although the physiological 
cause and, therefore, the necessity of this 
curious phenomenon has not yet been as- 
certained, yet, as it repeats itself in so many 
different groups of animals, it cannot be de- 
nied the importance of a fact. Hyatt’s || 
* Eimer : Zoologische Studien auf Capri II., Lacerta 
muralis coerulea. Leipzig, Engelmann, 1874. 
{The same: Die Zeichnung d. Vogel und Sauge- 
tiere. Wutrttemb. Naturwiss. Jahreshefte, 1883.. 
The same: Uber die Zeichnung der Tiere ; Zool. An- 
zeiger, 1882, 1883, 1884, and in the Zeitschrift Hum- 
boldt, 1885-88. The same: Mitteilungen tiber die 
Zeichnung der Siugetiere, Schmetterlinge u. Mollus- 
ken. Tageblatt der 28. Versammlung deutscher Na- 
turforscher u. Aerzte in Strassburg, 1885, p. 408. 
{Simroth: Versuch einer Naturgeschichte der 
deutschen Nacktschnecken und ihrer europdischen 
Verwandten, Zeitschrift. f. wiss. Zoolog. Bd. XLII. 
2 Grafin yon Linden: Die Entwicklung der Skulp- 
tur u. der Zeichnung bei den Gehiuseschnecken des 
Meeres : Zeitschrift f. wiss. Zoologie. Bd. LIX. 
|| A. Hyatt: Genesis of the Arietidae. Smithsonian 
