528 Diseases of the Genital Organs 



researches personally, but states : "a local organization was 

 set up in each case consisting of members of farmers' so- 

 cieties and veterinarians," to whom the details of the work 

 and the reports were entrusted. In the data published by 

 Stockman, it is not shown upon what plan the herds inves- 

 tigated were divided into "inoculated" and "controls." It 

 is quite easy, if one is acquainted with the history of each 

 animal, to change the face of statistics materially. Stock- 

 man rests his statistics upon the percentage of abortions 

 and ignores reproduction. He takes it for granted appar- 

 ently that if a cow does not abort, or rather is not observed 

 to abort, nothing else in her career is of interest. Thus, in 

 his table IX comprising 758 animals, 77.6 per cent, of vac- 

 cinated animals and 70.2 per cent, of the controls calved. 

 The efficiency of the controls fell 7.4 per cent, below the 

 vaccinated. The efficiency was low in both. The weakest 

 point in the data of Stockman is the failure to state the 

 time covered by the experiments. If 77.6 per cent, of the 

 vaccinated cattle calved during one year and were fertile at 

 the close of the year, the performance was certainly better 

 than if the period extended over two or three years, because 

 the efficiency, if the standard is set at one calf per annum, 

 would be 77.6 per cent., 38.8 per cent., and 25.9 per cent, re- 

 spectively. 



The Bland reports 1 offer by far the most valuable data on 

 record for a critical study of the influence of the vaccina- 

 tion of non-pregnant cows with living cultures of B. abortus. 

 The first report is stated to cover experiments during 191 1- 

 1913. At what date in 1911 the researches began is not re- 

 vealed, nor is it stated when in 1913 they closed. Since the 

 second report is stated to apply to 1914-1916, there was pre- 

 sumably no interval between the two reports. In the 1911- 

 1913 report it is claimed that of 263 animals vaccinated, 226 

 (86 per cent.) calved. There is no intimation that during 

 1911-1913 any cow calved twice or thrice. If the observa- 

 tions cover two years, the annual reproduction rate is 43 



1 Bland, G. R.. Epizootic Abortion Experiments, Oxfordshire County 

 Council: First Report, 1911-1913; Second, 1914-1916. 



