IMMUNITY FROM CONTAGIOUS DISSEASES. 
311 
the terms of which are parallel and alike,” I cannot restrain an 
equally positive assertion that the comparison is chiefly remark¬ 
able for being far-fetched and having no application to the ques¬ 
tion. There is nothing “ parallel and alike ” either in the means 
of attack and resistance or in the conditions under which the two 
contests are maintained. 
Although Dr. Curtiss thinks that the part of my theory which 
admits recovery to be due to the ability of the cell to resist the 
poison excreted by the microbe is correct, lie does not appear to 
free his mind from the belief that the contest is, after all, a phys 
ical one, and that it consists in the attempt of each to “swallow” 
the other. That a free, wandering, or amoebid cell might easily 
“ swallow ” or take into its interior a microbe, as supposed by 
Metschnikoff, is freely granted; but that the terms of this prop¬ 
osition can be reversed, and that a microbe with a smooth, rounded 
body, without external organs of any kind, without an opening in 
its body to take in its food, without the power of locomotion in 
the most restricted sense, should make a physical attack upon and 
“swallow” a cell, requires a free use of one’s imagination. 
But why does Dr. Curtiss insist that the combat between the 
man and the dog should be a “ well-ventilated ” room in order to 
be parallel with a combat between a microbe and a cell in the 
interior of the body ? Does not the most superficial knowledge 
of anatomy and physiology make it apparent that the interior of 
the body is not well ventilated, that a contest there, instead of 
being in the open air, is under liquid, and under a liquid which 
itself is not in contact with the air, and from which the cells of 
the body are continually drawing the oxygen necessary for their 
existence ? Then, again, the oxygen requirements of the man 
and dog are substantially the same, and any exhaustion of this 
element would affect each alike. On the other hand, the oxygen 
requirements of microbes are very different among different spe¬ 
cies, some of them requiring an abundant supply, and as a con¬ 
sequence, a large proportion of these species must have require 
ments different from the cells of the body. 
To make the comparison at all parallel and applicable, it 
would be necessary to assume that the room in which the man is 
