214 
Heredity. 
supply horse-owners with efficient farriers whose work can con- 
fidently he relied upon, will save the feet of many valuable horses 
from careless or clumsy manipulation, and will be a decided step 
towards the technical education of an important body of craftsmen. 
Charles Clay. 
HEREDITY. 
Thoxtgh the conception of heredity is far from being new, the sub- 
ject has recently been again brought prominently to the front, and is 
at present one of the most widely-discussed of biological problems. 
It has a special attraction and a peculiar interest for the agriculturist ; 
for whether his object be the improvement of live-stock or the im- 
provement of plants, the principle of heredity is that which must 
direct his efforts. 
In the recent developments of the problem, no investigator has 
imparted to the subject of heredity a greater interest, or endowed 
it with a higher fascination, than Dr. Weismann. His recently pub- 
lished work 1 on this subject is made up of a series of eight essays, 
arranged in the order of their original publication, from 1881 to 1 888, 
They deal with the following subjects : — (1) the duration of life, (2) 
heredity, (3) life and death, (4) the continuity of the germ-plasm as 
the foundation of a theory of heredity, (5) the significance of sexual 
reproduction in the theory of natural selection, (6) the number of 
polar bodies and their significance in heredity, (7) the supposed 
botanical proofs of the transmission of acquired characters, and (8) 
the supposed transmission of mutilations. Here is evidence of a 
sufficiently varied programme to afford any author an opportunity 
of showing a many-sided knowledge of the phenomena of life. ( Mie 
of the great charms of Darwin's works is their wealth of facts ; and 
if Dr. Weismann does not quite reach the standard in this direction 
of the great English naturalist, the reader is, nevertheless, bound 
to acknowledge the copiousness of illustration with which this 
volume is adorned. 
Heredity is defined as " that property of an organism by which 
its peculiar nature is transmitted to its descendants. From an 
eagle's egg, an eagle of the same species develops ; and not only are 
the characteristics of the species transmitted to the following genera- 
tion, but even the individual peculiarities. The offspring rescmMc 
their parents among animals as well as among men." But the mind 
demands more than a mere definition, and Weismann endeavours to 
supply this, his argument being somewhat as follows : — 
Certain minute organisms of very variable size occur in stagnant 
water, in mud, in damp earth, and elsewhere, and are fre- 
quently to be obtained by infusing any animal matter in water, and 
1 Eesayi upon Heredity and Kindred Biological Problems. 15y Dr. August 
Weismann. Authorised Translation, edited by Hdward I!. Poulton, Scliuor 
Kohonland, and Arthur K. Shipley (Oxford: Clarendon Press, 18H'.t). 
