796 Recent Literature. [ October, 
“Ruling out the lost or transient forms which are not perpet- 
uated, we see that the fundamental law here, as elsewhere, is, that 
all the characteristics are inherited after they are once introduced. 
“In former essays, especially written for this purpose, I have 
tried to show that there was such a general law which is so plain 
and simple that I have wondered that no authors have made it 
the basis of investigation except Professor Cope and myself. In 
every series of animals which I have studied, the same fact 
appears, namely, that in a given number of generations, inherited 
characteristics of every kind tend to appear in the descendants at 
earlier stages than that at which they first occurred in the ances- 
tral forms. Whether characteristics are normal or abnormal, 
provided they are fixed in the race either by the action of natural 
selection or by the direct working of physical causes, they are 
inherited according to this law. 
“The law of acceleration appears to me, at present, to show 
the manner in which characteristics, which are perpetuated, finally 
either disappear or become fixed in the young, or even in embryo. 
This conclusion may be followed out by any one who will arrange 
a series of animals or their shells, according to their adult affini- 
ties and their developmental characteristics. He will then see 
that adult characteristics which are introduced in ancestral forms, 
tend to reappear at earlier and earlier stages, as he travels along 
the series.” 
Marey’s Anrmat Mecuanism1—Although the main principles 
and facts contained in this interesting volume have been already 
given to the public by way of abstracts in scientific journals, yet 
it is not too late to call the attention of zodlogists to the value of 
this work in their studies. Animal mechanics has been much 
while if we knew exactly at what pace an animal does the best 
work, whether he be required for speed or for drawing loads, we 
could all be Mr. Bergs and prevent much suffering in our no lest 
of animals, the horse, and that only less useful creature, the 0%; 
while in the good time coming, when electricity may serve a5 © 
motive power instead of steam, animal mechanics will reach its 
apotheosis in a flying machine adapted to the wants of our every” 
day life, as well as of the traveler, soldier, and all whose calling 
ey impel them to seek a means of locomotion in rapid aerl@ 
ansit. 
1 The International Scientific Series. Vol. xi. Animal Mechanism: ® Loss 
on terrestrial and aerial Locomotion. By E. J. MAREY, Professor at the Colleg Pe 
France, etc., with 117 illustrations, New York, D. Appleton & Co., 1879 Ms 
Pp. 283. $1.75. 
