vi PREFACE 



carried out at the Brown Institution during 1910, 191 1, 

 1912, and the first three months of the present year. 



These investigations have thrown a considerable 

 amount of work on the staff of the laboratories, and 

 here we should like to record the industry and care 

 with which the chief attendant, Mr. Frankham, has 

 performed the various duties allotted to him. 



The book consists of nine chapters, and throughout 

 the descriptions and details refer to cattle unless 

 otherwise specified. The first five chapters are allo- 

 cated to the history of the disease, its importance to 

 stockowners and breeders, its clinical features, methods 

 of diagnosis and treatment, and the pathological lesions 

 found post mortem. 



In Chapter VI. we deal with the cultivation of 

 Johne's bacillus, and describe in some detail the ex- 

 periments that have been carried out in this direction 

 by different workers from the time of Johne and 

 Frothingham to the present day; we also include a 

 description of the bacillus, and the appearance of the 

 cultures on fluid and solid media. 



In Chapter VII. we describe the method of preparing 

 a specific diagnostic vaccine, and the earliest experi- 

 ments carried out with avian and other tuberculins are 

 also given. Chapter VIII. contains some results with 

 agglutination and complement- fixation tests, which 

 were performed by Dr. C. C. Twort. Chapter IX, 

 contains most of the recorded experiments with infec- 

 tive material and pure cultures of the bacillus. Here, 

 too, we include a large number of experiments by 

 Dr. C. C. Twort and Mr. T. Craig on the small labora- 

 tory animals. 



Research work on a disease which affects any of the 

 larger domesticated animals is necessarily very costly, 

 not only from the expense of the experimental subjects 



