21 



of the percentage named. Not because I had not expected to find 

 the bacilli — I have been convinced for several years that persistent 

 search would show their presence in such cases as those that are here 

 recorded — but because the amount of dilution to which the organ- 

 isms must be subjected diminished immensely the chance of their 

 being found at all. In no case have they been seen in large num- 

 bers, but equally in no case has a diagnosis been made where there 

 was the slightest doubt of the appearance under the microscope. 



The large number of cases in which these organisms have been 

 found seem to me to indicate their presence in a still greater propor- 

 tion of cases, if only a sufficiently thorough examination of all the 

 milk could be made. This of course is out of the question, but the 

 results here given seem to establish, beyond a doubt, the fact that 

 milk coming from cows with no definite lesion of the udder may 

 contain the infectious principle of tuberculosis, if the disease be 

 present in other portions of the body of the animal. Also, that this 

 presence of the infectious principle is not merely a so'\eut[fic possibility 

 but an actual probability , which we should be thoroughly aware of and 

 alive to. 



Other interesting facts shown are these : that the cream after rising 

 is quite as likely to be infectious as the milk, because the bacilli were 

 foun'i in the milk nine 'times after the cream had risen, and in the 

 cream eight limes after it had separated from the milk. 



In regard to the constancy of the occurrence of the bacilli in the 

 milk, in two of the ten cows in whose milk the bacilli were found, but 

 one sample of the milk was examined ; and the bacilli were found in 

 one sample out of several examined at different times, in two cases 

 In the remaining six cows, bacilli were found two or more times in 

 different samples of milk. So that, as far as they go, these results 

 seem to indicate that the bacilli are present with a fair degree of 

 constancy. At the same time it should not be surprising if one 

 examination was successful and others failed, because of the 

 chances against success, owing to dilution, which were spoken of 

 above. 



In nine of the seventeen cases the time of the milking and the por- 

 tion of the milk used were noted ; that is to say, a sample was taken 

 from the first of the milking, or the last of the milking, and then 

 cover-glasses made from the milk or cream. In these cases bacilli 

 were found in the cream three times, and in the milk four times, from 

 the first of the milking ; in samples from the last of the milking, in 

 the cream no times, and in the milk four times ; and this too seems 

 to show an interesting point, viz., that the bacilli, if present at all in 

 the udder, are not washed out entirely b}^ the first manipulations of 

 the teats, but may be supposedly present in any portion of the milk. 

 The converse is also indicated, that the manipulation of the udder in 

 the process of milking does not express the bacilli from the tissue into 

 the latter portion of the milk, but that, as before, they may be sup- 

 posed to be pretty evenly distributed in all parts of the udder if they 

 be present at all. 



