132 DOMESTICATED ANIMALS AND PLANTS 
shows the importance of early food and care for the young of 
our domesticated species. 
Plants are easily dwarfed, either by scarcity of food or by 
repeated planting of immature seed. Many species have their 
dwarf varieties, though others are artificially produced by graft- 
ing on other and smaller species, as, for example, the pear, 
which is dwarfed by grafting upon stock of the quince, 
Overdevelopment, or giants. In normal development and 
differentiation, growth should not only proceed to the proper 
point, but it is fully as important that it sop at that point. If it 
does not, then overgrowth takes place and a giant is produced. 
As the dwarf is the result of too little cell division and too 
few cells, so the giant is the product of too much cell division 
and too many cells; that is to say, of growth that did not stop 
at the right point. 
Giants are common in man and frequent in cattle. So far as 
is known to the writer, they are unknown in horses, sheep, and 
pigs, though these species can all be increased in size somewhat 
above the normal by extreme feed and care in early life as well 
as by selection of parents above the normal. 
Neither giants nor dwarfs possess special interest to the 
improver, because if we needed a smaller or a larger race than 
the normal, we should not depend upon these occasional indi- 
viduals, which are abnormal, to produce it. Their mention here 
is for the purpose of making the student somewhat intelligent 
on the processes of life, to do which requires a number and 
variety of examples involving various phases of abnormal 
development. 
Arrested development of a single character or part. Dwarfing 
may take place with respect to one or more parts or characters, 
while others proceed to normal development, giving a more or 
less distorted body. 
This form of abnormality has many manifestations. In some 
cases, for example, a part is entirely missing, as if the unit char- 
acter had been lost, as in a case, known to the writer, of a man 
