HEREDITARY INEFFICIENCY. 303 
essentially alike for a period after their birth. The crab 
continues and develops an active life. The Sacculina 
thrusts its feelers into the body of the crab on which it 
is to feed. Its organs of eating and swimming disap- 
pear, All structures connected with independent life 
become atrophied, and finally nothing is left of the Sac- 
culina except its saclike body, its feelers or roots rami- 
fying through the blood vessels of the crab, and its 
reproductive organs by which the brood of parasites is 
kept alive. When the habit of parasitism is once estab- 
lished, the struggle for existence simply intensifies it 
from generation to generation. 
The fittest Sacculina is the most degenerate one. In 
like manner whenever a race or family of men has fallen 
away from self-helpfulness the forcés of evolution inten- 
sify its parasitism. The successful pauper is the one 
who retains no capacity for anything else. The loss of 
all other possibilities is the best preparation for the life 
of the sneak thief. 
Recent studies, as those of Dugdale, McCulloch, and 
others, have shown that parasitism is hereditary in the 
human species as in the Sacculina. McCulloch has 
selected the Sacculina for special illustration of the 
results of like processes in the human family. Like 
produces like in the world of life. Those qualities in 
the grandparent which made him an outcast from so- 
ciety or a burden upon it reappear in the father and 
again in the son. As in one case, so in the others, they 
determine his relation to society. The pauper is the 
victim of heredity, but neither Nature nor society recog- 
nises that as an excuse for his existence. The forces of 
Nature take no account of motive and are no respecters 
of persons. Dugdale has shown that parasitism, pauper- 
ism, prostitution, and crime reappear generation after 
generation in the descendants of “ Margaret, the mother 
21 
