494 
PATHOLOGY: MELTZER AND WOLLSTEIN 
pneumonia.' In the last six or seven decades many more experiments 
have been made on the section of both vagi; but all investigators have 
accepted Traube's interpretation, namely, that the section of the vagi 
does not cause directly any changes in the tissues, but that the section 
of the nerves leads to a 'foreign body pneumonia.' 
In the above mentioned numerous experiments, as a rule, both vagi 
were cut; not very many experiments were made by cutting only one 
vagus. But when such an experiment was made, it was found practi- 
cally invariably that cutting of one vagus produced neither any clinical 
effect during life nor were there pathological lesions of the lung at 
autopsies. I may add that our own experimental experience supports 
this finding : Cutting of one vagus of a normal dog never leads to a pul- 
monary disease or lesion. 
In the course of the last eight years we carried out in this laboratory 
numerous experiments on the production of pneumonia by direct injec- 
tion through the unoperated larynx into the bronchi of normal dogs of 
various micro-organisms capable of producing various forms of pneu- 
monia. Most of our experiments were recently made with intrabron- 
chial injections of culture of pneumococcus type I, and it was established 
that the degree of the disease which it produces or the length of time 
required for the fatal outcome depend upon the virulence of the organism 
as well as the quantity of the culture injected. Recently a long series of 
such experiments were carried out with a view of studying the direct 
action of vagus nerves upon the development of pneumonia. Since in these 
experiments the nerves of the oesophagus and of the larynx remained 
intact, any acceleration in the development of the disease or the pulmon- 
ary lesion could be ascribed only to the interruption of the nervous 
impulse normally transmitted through the intact vagus nerve to the lung 
tissue. We shall not enter here into the details of the experiments; but 
merely state briefly that: In one series of experiments one vagus was cut 
but no organisms insufflated; these animals, as mentioned above, remained 
normal. In another series of experiments a definite quantity of the cul- 
ture was insufflated in normal dogs. These animals either remained alive 
or died with some pulmonary lesions many days after the injection. In 
a third series the same culture and the same quantity of it was insuf- 
flated on the same day and under the same condition as in the last men- 
tioned series; but in these animals one vagus was cut either four days 
or ten or more days before the culture was insufflated. These experi- 
ments brought to light a striking result. In the series in which one vagus 
was cut ten or more days before the insufflation of the culture nearly all 
