522 Tuberculosis. 



The possibility of a couceptional or gerniinative transmission of tuberculosis 

 has never been demonstrated and is, in addition, highly improbable. Tubercle 

 bacilli have never been found in a germinal vesicle or in the egg. Besides, infection 

 of the egg would result in its destruction before it could mature. It is true that 

 Maffucci, and later Baumgarten, found that in hens' eggs, that were infected 

 artificially into the white with avian tubercle bacilli, normal cell division took 

 place and occasionally the embryo developed completely. However, what has been 

 found to be true for the meroblastic chick egg does not necessarily apply to the 

 egg of the mammal because infection did not take place directly in the egg cell 

 but in the surrounding albumen and consequently the tubercle bacilli would still 

 have to pass through the area vasculosa, the analogue of the placenta, before they 

 could reach the embryo (Wassermayer, Bongert). However, the chicks hatched 

 from eggs thus artificially infected always died of tuberculosis after a short time. 



While in tuberculosis of the urino-genital tract, and especially in tuberculosis 

 of the epididymis tubercle bacilli are frequently present in the spermatic fluid, 

 infection of the ovum could occur only by the simultaneous introduction of a 

 bacillus with the spermatozoon into the ovum (bacilli have never been demonstrated 

 in spermatazoa). These theoretical conclusions are in harmony with the results 

 obtained from actual experiments. Gaertner, Cornet and Hansen never succeeded 

 in their attempts to infect the offspring of rabbits or guinea pigs by the previously 

 infected male. 



The frequenc}^ of tlie disease bears a close relation to the 

 age of the animal. Young animals are in general more sus- 

 ceptible than older ones, yet the disease is more frequently met 

 with in the latter for the reason that they have been exposed 

 to infection for a longer time. As a matter of fact the per- 

 centage of morbidity increases gradually from the suckling 

 period, year after year, and in cattle more than 50% of all 

 cases, as revealed by the tuberculin test or in the abattoir, are 

 found in animals over six years of age. 



In the abattoir of Budapest in the year 1899, 9,046 tuberculous cattle were 

 classified as follows: 3 at 3 to 4 weeks, 1 at 5 months, 4 at 7 to 9 months, 12 at 

 one year, 39 at 2 years, 81 at 3 years, 118 at 4 years, 326 at 5 years, 1,223 at 

 6 years, and 7,239 over 6 years (among the latter .5,173 Hungarian draft oxen). 

 In Denmark, according to Bang, 40,624 cattle (1898-1904) gave the following results 

 after first tuberculin tests: of 5,5.59 calves under six months, 12.1% reacted; of 7,744 

 cattle from 6 to 18 months, 27.5%; of 5,047 head from IS to 30 months, 38.67o; 

 of 10, 350 head from 21/0 to 5 years, 44.9%, and of 11,924 cattle over five years, 48% 

 reacted. Of the latter 79% were already infected at the age of two years. In 

 Norway, according to Malm the tuberculin reaction in calves under 6 months reached 

 1 to 2%; at 6 to 12 months, 1.5 to 3.4%; in 1 to 5 year old cattle 4.3 to 7.9%, 

 and in still older animals 5.6 to 10.4% reacted. Naegeli reports similar conditions 

 among human beings; 1 to 5 years gave 17% of reactions; 5 to 14 vears, 33%; 

 14 to 18 years, 50%; 18 to 30 years, 96% of reactions. 



The sex influences the prevalence of tuberculosis only in 

 as far as it affects the conditions under which the animals may 

 have been kept. The disease is most prevalent in dairies com- 

 posed of cows of the more domesticated breeds. Among these we 

 .frequently find from 70 to 80% and more, of reactors. Steers and 

 bulls of these same breeds, which are rarely allowed to reach the 

 same ages, give a much lower percentage. Compared with 

 these figures the percentage among the gray cows and bulls 

 of the steppes which are kept mostly in the open air are much 

 lower than in stable-fed oxen of the same breed that are worked 

 for years (see p. 519). 



In the German Empire the frequency of tuberculosis was found in the abattoirs 

 as follows: Oxen 20.04%, bulls 15.82%, cows 27.13%, yearlings and young cattle 

 6.2%, calves 0.30%. In the abattoir at Budapest in 190.3" the following" results were 



