426 
DR. A. WALLER ON THE ALTERATION OF THE 
racteristic of the nervous medulla. In some cases the coagulated particles are very 
uniform in size and appearance, averaging y^o^th of an inch. In others, the limits 
between the maximum and minimum dimensions are far greater, namely, from -y sV oth 
to ii;^th of an inch. The diameter of the altered tubes, examined in the ordinary 
manner in water, is about a fourth smaller than that of the sound ones, and in many 
instances the tubular cylinders appear wanting, and the medullary particles to have 
escaped from the cylinder, and to be merely held together by the neurilerna which 
surrounds the whole nerve. After the application of potash, the diameter of the 
altered and unaltered nerves is as nearly as possible the same. This equalization of 
the two is produced almost entirely by a decrease in the size of the sound tubes, 
which swell considerably in water, and afterwards contract by the application of the 
alkali. It is therefore probable that the difference of size at this stage between the 
altered and unaltered nerves arises from the former not absorbing so much within 
them as the latter. Whether this arises from a ruptured state of the membrane or 
from a chemical change of the medulla, is not evident. After the surrounding tissues 
have been removed by potash, the tubular membrane offers no signs of rupture, and 
the medulla appears less disorganized than before the denudation. The disjointed 
condition of the medulla is greatest towards the extremities. A portion of each nerve- 
tube is frequently so disorganized as to be carried away among the tissues dissolved 
by the alkali. The circular rim so frequently presented by the extremity of the tubes 
is absent. We often observe around the healthy nervous branches, and the papillary 
nerve in particular, a common sheath or neurilerna fitting closely to the nerve. After 
disorganization has attained this degree, it appears to form a kind of loose pouch 
around the nerve and separated from it by an interval of ywFoth of an inch. This 
pouch appears to form the sole investment of the curdled medullary particles, which, 
as we have stated, previous to the action of the alkali, appear void of any tubular in- 
vestment. As we ascend towards the brain the disorganization appears to decrease, 
the coagulated medulla is more apt to assume the oval form, and at some places it 
presents its double contour apparently unaffected. The effect of decomposition in 
the unaltered and altered nerve is similar to that in the former stage. In consequence 
of the above changes the disorganized nerve is more opake than the unaltered one. In 
the tubercles some of the ramifications of the tubes belonging to common sensation 
become disorganized after the section of the corresponding glossopharyngeals. These 
alterations take place in the same period and in the same manner as in the papillary 
nerves. With this exception, all the other nerves of the tongue, which comprise those 
of common sensation and of muscular action, remain unaltered. The muscular fibres 
of the papillae are slightly altered at this period ; their transverse striae are not so 
distinct as on the healthy side, while their longitudinal ones are more so. The fibre 
itself is usually paler, narrower and more wavy in its course. 
The capillaries are either much congested with dark blood, or they are completely 
empty and scarcely to be detected. 
