(pli ee) 
2. They afford fresh illustrations of the manner in which 
the physiological isolation of an incipient species may be 
brought about.* 
3. They do not support the assertions of Haeckel and 
Quatrefages as to the possibility of Lepidopterous hybrids 
continuing their race apart from admixture with either parent 
form. 
4. They show that the statement of Focke as to the great 
variability of the offspring resulting from the crossing of a 
plant hybrid with one of the parent species holds good in the 
case of insects. 
5. What Standfuss speaks of as the prepotency of the 
phylogenetically older of the parent species is probably only 
another expression of the principle established by Darwin, 
that in many cases crossing causes reversion to a remote 
ancestor, 
6. The general conclusion as to the prepotency of the male 
parent accords so far with one result of Mr. F. Galton’s 
investigation of the late Sir E. Millais’ breed of Basset 
hounds. 
7. The result of crossing a parent species with a gradually- 
formed local race, though less in degree, is much the same in 
kind as that of crossing two distinct species. 
8. The result of crossing the normal form of a species 
‘with a sporadic aberration of the same species appears to 
show that the latter stands biologically on an entirely dif- 
ferent footing from the regularly developed variety, even 
though it may indicate (as alleged by EKimer and by Jordan) 
the direction in which variation for that species is possible. 
With Standfuss’s instances may be compared the well-known 
case of the “ otter-sheep ”’ (Darwin, ‘ Variations of Animals 
and Plants under Domestication,’ 1868, vol. 1, p. 100), 
which similarly, when crossed with a sheep of ordinary breed, 
gave no true intermediates. 
9. Certain experiments with aberrations of this kind, of 
which exact numerical records have been kept for several 
** This has been demonstrated ona complete scale by Jordan, 
“ On Mechanical Selection,” Nov. Zool., 1896, pp. 426-525.—F. A. D. 
