238 GENERAL BIOLOGY 



on in the germ-cell itself, which is involved in 

 differentiation and later becomes a causative agent 

 for disease. Since we must look upon disease as a 

 process, and a process brought about, in the majority 

 of cases, by the activity of poison-producing, para- 

 sitic bacteria, it is evident that there cannot be 

 anything in the germ-cell, even of a diseased person, 

 to produce the disease unless the germ-cell itself 

 contains the microbe. With one or two exceptions 

 this is not the case, since the disease-producing 

 bacteria are usually localized in certain regions of 

 the soma. Equally obviously, disease-processes that 

 are merely alterations of normal metabolism can- 

 not, in themselves, be inherited. 



On the other hand, the disease-process is usually a 

 sort of resultant of a parallelogram of forces, of which 

 the strength of the invading microbe is opposed to 

 the resistance of the victim. Now, not only may 

 the resistance, i.e. the power of the body to produce 

 substances that counteract or nullify the effect of 

 the toxins, differ markedly in different individuals, 

 but also this power, being a function of the physical 

 organism, may be inherited in varying degrees. We 

 are therefore justified in speaking of the inheritance 

 of a tendency toward certain diseases, although what 

 we really mean is the inheritance of a low resistance 

 on the part of the body to the disease, and the 

 consequent ease with which the disease is contracted. 

 For in every case there must be a new infection in 

 each generation. It is believed that even leprosy, 

 one of the most dreaded of human afflictions, the 



