340 
C. M. DAY. 
A BACTERIOLOGICAL STUDY OF EQUINE FISTULAE. 
By C. M. Day. 
A paper read before the Iowa State Veterinary Medical Association. 
Since the general acceptance of the doctrine that the pres¬ 
ence of certain parasitic microbes is an essential feature of the 
suppurative process we can no longer be satisfied to refer Poll- 
evil and fistulous withers to traumatism only, but must in this, 
as in every other instance, apply the methods of bacteriological 
analysis. These conditions are peculiar to the equine species, 
and from their seriousness, frequency and intractability are of 
great practical importance. This study has been made to the 
extent of identification of the species and virulence of some 
micro-organisms found in the pathological elements from the 
cases mentioned. 
The part of the animal economy generally known as the 
poll is the region immediately behind the ears, on the superior 
part of the neck. The skin very thick on the median line, 
thinner on the sides, with a thick layer of connective tissue, 
more or less infiltrated with fat, just beneath; the cord of the 
ligamentum nuchae, which is attached to the occipital bone and 
more or less covered with the cervico auricularis muscle on each 
side, and on the same level the terminal insertion of the sple- 
nius muscles, forming an elevation which is covered with the 
aponeurosis common to that muscle, and the small complexus 
which makes an apparatus of retention of great resistance to 
the organs of the region; another layer, composed of the large 
tendon of the great complexus, the small oblique muscle of the 
head, the great oblique, and under them the posterior great 
muscles of the head, a serous sac, assisting the gliding of the 
cord of the ligamentum nuchae over the atlas, and finally a 
skeleton of the region, atlas, axis, occipital crest and the occip- 
ito-atloid and the atlo-axoid articulations. These are the 
principal anatomical features of this region. 
The withers is the part of an animal just posterior to the 
cervical region. It is formed by the superior spinous processes 
