GERM CELL INFECTION. 59 



mission takes place in man, and the likelihood of 

 its occurrence could be proved only by finding the 

 micro-organisms actually within the ovum of 

 sperm cell. 



Definite examples of this type of transmission 

 are found in insect life, particularly among ticks. 

 The piroplasmas of Texas fever and of Rhodesian 

 fever of cattle, the spirillum of South African 

 tick fever of man, and the virus of Rocky Moun- 

 tain spotted fever are all transmitted to the lar- 

 vae of the next generation through infection of 

 the ova of the corresponding ticks. 



Since it does occur in other forms of life, it 

 would not be surprising if it also occurs in man. 

 In that form of inherited syphilis in which the 

 child derives the infection from the father, the 

 mother apparently remaining uninfected, the virus 

 may have been introduced into the ovum by means 

 of an infected sperm cell. Even in this case, how- 

 ever, it is virtually impossible to rule out the exis- 

 tence of a latent infection of the mother. And if 

 such infection does exist, the spirochetes may have 

 reached the embryo by way of the placenta, in- 

 stead of through the ovum. Possibly the recently 

 discovered test for syphilis (fixation of comple- 

 ment) will throw some light on this phase of in- 

 herited syphilis, since it renders possible the diag- 

 nosis of the disease in the mother regardless of 

 positive clinical manifestations. 



It is equally, or perhaps more, uncertain as to 

 whether tuberculosis is ever inherited through in- 

 fection of the germ cells. Tubercle bacilli have 

 been found in the testicular secretion in both man 

 and animals. In such cases the tuberculosis is of 

 an advanced type, resulting in early death. Even 



