Congenital Infections of Calves 657 



partly the apparent contradiction between his researches 

 and ours. The researches of Jensen were faulty in several 

 respects : 



(1) There is no evidence that the calves selected were 

 free from alimentary infection when born. 



(2) Details, or even general outlines of the feeding are 

 wholly wanting. 



(3) The controls had diarrhea, which was slower in de- 

 veloping and less fatal than in the inoculated animals, but 

 otherwise showed no differential characteristics. 



Accordingly it appears that the conclusions of Jensen were 

 based upon wholly unreliable grounds and that he did not in 

 fact clearly induce dysentery experimentally. So far as I am 

 aware, calf dysentery can not be caused reliably by any 

 known bacterium, although, reasoning by analogy and view- 

 ing it clinically, its infectious character is unquestionable. 

 The experimenter is faced, as in abortion, with the impossi- 

 bility of determining in advance the freedom of the experi- 

 mental animal from the infection under consideration. 

 When there is added the utter impossibility of clearly de- 

 fining white scours, the difficulty of securing definite experi- 

 mental data upon its etiology is apparent. The conclusion 

 can not well be avoided, since in most cases of calf dysentery 

 there is an abundance of a comparatively limited variety of 

 organisms present, and those recognized are reasonably uni- 

 form in the different patients, that the disease is due to in- 

 fection, and that the bacteria multiplying disastrously in 

 the alimentary tract of a sick calf would likewise multiply, 

 though not necessarily disastrously, when properly placed 

 in the digestive tract of another calf. Clinically this is ap- 

 parently true. White scours breaks out in large stables and 

 pursues the relentless course of a scourge, causing a mor- 

 tality of ten to one hundred per cent, for months at a time. 



Apparently therapeutic evidence also indicates the infec- 

 tious character of the disease, though this may be mislead- 

 ing. When a horse, by means of repeated inoculations, is 

 rendered highly resistant to the dominant organism asso- 

 ciated with white scours, his blood serum injected into a 

 42 



