13 



term, as in the case ot foot-and-mouth 

 disease. 



ot). The animal species, which are 

 sensitive to the germ, produce sera of a 

 very real preventive value: thus serum 

 active ajiainst loot-aud-mouth disease can 

 only be obtained from cattle and porci- 

 nes; serum against hog-cholera only from 

 sheep, and so forth. 



This last character is one of those 

 which are still rather uncertain in medi- 

 cal and veterinary littérature; it is in this 

 way that, in the case of the contagious 

 epithelioma of birds, the conclusions are 

 categoric and deny the serum any pre- 

 ventive or curative properties. To sus- 

 tain this last assertion, i. e. "that sensi- 

 tive species produce a preventive serum", 

 the first indication was to control the ex- 

 periments of other research-workers on 

 this subject, by repeating them, avoiding 

 causes of error which might have left 

 margin for the obtaining of negative re- 

 sults. That was the reason for the 

 undertaking of this work. 



Research work carried out at our 

 Station showed that, here as elsewhere, 

 these errors had been of dual nature; 

 insufficient ! doses and a pseud o-superi- 

 munisation. 



A) Insufficient Doses. There is a ge- 

 neral tendency to carry out the investiga- 

 tion of sera with insufficient doses, a fact 

 which frequently leads to the denying 

 of any value to antibacterian and anti- 

 toxic sera of great curative value, such 

 as the one against bubonic plague, teta- 

 nus, etc. In the cases of the filtera- 

 ble germs MOUSSU, in preparing serum 

 against foot-and-mouth disease by injec- 

 tions of virulent blood, obtained a serum 

 certainly efficacious, but tried its effect 

 with 50 cm' which in this case must su- 

 rely have corresponded to one third of 

 the efficient dose. On the other hand, 

 when the research- workers use conside- 

 rable doses the results are positive in 

 foot-and-mouth disease as in diseases pro- 



duced by other filterable germs, unless 

 another cause of error intervenes. 



In vaccination, REYNAUD, among 

 others, was able to immunise calves with 

 250 cm* of a convalescent's serum; and 

 STRAUSS, CHAMBÓN and MENARD, 

 with more or less a litre. (Pos-sibly an in- 

 tense super-immunisation might reduce 

 this dose to its tenth part ; in another pu- 

 blication we will return to the subject). 

 KUNIO SATA ascertained the formation 

 of antibodies in rabbits inoculated either 

 cutaneously or in the cornea. 



In sheep-pox, DU CLERC immunised 

 the animals wilh 190 cm^ of cured sheep's 

 serum and BORREL was even able to ob- 

 tain serum of practical use, immunising 

 with a dose of 15 to 20 cm^. 



In foot-and-mouth disease, various 

 research workers verified that the serum 

 of animals, that had recovered from 

 the disease, immunised at the dose of a 

 litre and LOEFFLER, super-immunising 

 cattle, reduced the preventive dose to 

 100 to 150 cm*, a dose which can be 

 further reduced to less than 80 cm* wi- 

 thout concentrating the serum. 



In Cattle Plague, a few hundred 

 centimetres of the serum of a convales- 

 cent animal are already of use in the 

 prevention of the disease, but KOLLE 

 and TURNER, NICOLLE and ADIL BEY 

 and others, by means of supei'imraunisa- 

 tion, reduced this dose to about 20 cm» 



In hog-cholera, the serum furnished 

 by superimmunised animals is of the 

 most potent kind since it prevents infec- 

 tion when employed in doses of less 

 than 10 cm*, but as in the case of all 

 the other sera against filterable micro- 

 organisms, its curative properties are^ 

 practically non-existent, and only demons- 

 trable by the use of enormous doses 

 right in the beginning of the disease. 



¡n chicken pes/, JOUAN and STAUB 

 were alile to immunise chickens with 

 less than 1 cm* of serum obtained front 

 chickens. 



