54 
ficium on the side, which may in addition be very narrow or 
even entirely covered with folds of the mucosa. 
Still more difficulties for conception may be present in 
the cervical canal, which may be impassable on account of 
being bent, narrow, or obstructed with folds of the mucosa. 
Quite frequently also a viscous and greasy secretion blocks 
the canal, and is then the cause of sterility. 
Even apparently insignificant changes of the portio or 
of the canal, which hardly obstruct during normal conditions, 
may produce stenosis in the hyperemia of the estrum. I 
found that often through the examination of bulling cows. 
The same observation applies to the uterus proper, where 
the injected mucosa becomes still more hyperemic with the 
hyperemia of the estrum, and is then capable of obstructing 
the passage of the spermatozoa. This is especially evident 
on the os uteri externum, where sometimes a part of the 
swollen mucosa covers the orificium entirely. (See Fig. 13.) 
The cow of this illustration had calved in May, 1907, and 
has had an estrum three times after that. The orificium was 
swollen, injected and secernating; there were large folds of 
the mucosa round the orificium, which covered the entrance 
into the canal entirely. 
Sometimes the mucosa of the canal protrudes from the 
orifcium also during the heat-free time and can be easily 
recognized by its dark red color; during the estrum this 
mucosa increases still more in size and obstructs the canal 
completely. Similar conditions may exist in the whole 
length of the canal, but are especially frequent in the middle 
and near the os uteri internum. 
It is therefore necessary to extend the observation to the 
direction of the cervical canal, to its width, to the color of 
the portio and to the state of the mucosa; it is not sufficient 
to be able to introduce a catheter into the uterus, when the 
animal is not in heat. 
The best procedure is to examine the animal during the 
estrum, so as to be able actually to see the stenosis. 
