Orr’s Views 
of the environment in determining or modifying 
organisms. 
The similarity of the views of Orr and 
Lamarck is best seen by comparing their re- 
spective explanations of the long neck of the 
giraffe. Lamarck thought that this was the 
direct result of continual stretching. The animal 
continually strains its neck in the search for food, 
hence it grows longer as the individual grows 
older, and this elongated neck has been trans- 
mitted to the offspring. Orr writes, on page 164 
of his Development and Heredity: “The giraffe 
seems to present the most remarkable illustration 
of the lengthening of the bones as the result of 
the frequent repetition of such shocks. As is 
well known, this animal feeds on the foliage of 
trees. From the earliest youth of the species, 
and the earliest youth of each individual, it must 
have been stretching upwards for food, and, as is 
the custom of such quadrupeds, it must have 
constantly raised itself off its forefeet, and, as it 
dropped, must have received a shock that made 
itself felt from the hoofs through the legs and 
vertical neck to the head. In the hind legs the 
shock would not be felt. It is impossible to 
imagine that an animal which, during the greater 
part of every day of its life (both its individual 
and racial life), performed motions so uniform 
and constant, would not be peculiarly specialised 
as a result. The forces acting upon such an 
B 17 
