aS 
2. Changes of the mucosa which prevent the implanta- 
tion of the ovum, or cause an early abortion. 
3. Lesions of the ovaries, which are generally second- 
ary, or rather, reflexive processes, and which prevent the 
normal ovulation, as cystic degeneration and corpus luteum 
persistens. 
So far as the stenosis is concerned there cannot be any 
doubt that it can be the cause of sterility. If one considers 
the anatomy of the bovine genital apparatus, the narrow 
and indirect cervical canal, the long and curved uterus horns, 
whose lumen is so very small, specially in the apices, one 
must admit that even a little change can obstruct the pas- 
sage of the spermatozoa. In addition to that the mating act 
in cattle is a very short and quick one, the quantity of dis- 
charged semen is comparatively small, and has to be depos- 
ited on a definite place. 
It is generally admitted that the sperma ought to be 
deposited in the cervical canal; an ejaculation into the 
uterus proper is uncertain and hardly necessary. Zschokke 
states that the immission of the penis into the uterus is 
unnecessary and unlikely; it is however necessary that the 
sperma be deposited in the os uteri externum, as conceptions 
are prevented if the penis is not introduced far enough. 
The changes one finds so often in the cervix of sterile 
cows are capable of preventing the passage of the sperma- 
tozoa entirely or of making it at least very difficult. 
During the normal estrum the cervical canal is open, the 
os uteri externum forms a round, wide and funnel shaped 
opening which leads into the entirely passable cervical canal; 
the latter is now so straight that it may be passed by the 
largest catheter without difficulty. The canal is filled with 
a thin, clear and alkaline mucous matter which pours into 
the vagina. 
It can be easily understood that the above mentioned 
lesions of the cervix may prohibit conception. The swol- 
len, irregular and ragged portio vaginalis often has the ori- 
