78 
society. The first three cows all became pregnant after the 
one cohabitation, but only one of the others did. None of the 
animals showed any lesions after two careful examinations. 
I saw also many other cases where the bulls did not breed 
well, and it is necessary to keep this possibility in mind, in 
passing a judgment on a treatment of sterility. 
Sometimes in a herd of heifers only a few are pregnant; 
then there is most certainly something wrong with the bull. 
If the bull is together with the cows in a pasture, then the 
breeding can not be observed and controlled; it may happen 
that a number of cows come in heat at the same time and the 
bull can then not be expected to cover them all well. Even 
a young bull may early become a poor breeding animal. 
The success of the treatment depends, of course, chiefly 
on whether benign or more or less severe cases are the 
subjects. 
In the result of the treatment the date of commencement 
of the pregnancy after the treatment, must also be considered 
and not only that the animal becomes pregnant at all. 
In the following tabulations only such herds are included 
that were under observation and treatment for a considerable 
time, and of which I have all the important observations and 
the breeding lists, and in which I had the chance to make 
the final diagnosis of pregnancy. Single animals and herds 
where I undertook the treatment only casually, are not in- 
cluded. 
With the exception of the first eight herds, I have not 
used the pressing out of the yellow bodies, to any extent. 
The number of cows under observation was 3,527, 1,513 of 
which were treated once or more often on account of 
metritis, or of irregularities of the estrum. All the animals 
came under treatment in an early stage. 
Of these cows 1,176, or 78%, became pregnant again. 
The value of the pregnancy, however, as I have already 
stated, depends very much upon the length of time which 
has elapsed before the fecundation. Therefore, in 1,004 
