320 
MR. J. L. CLARKE ON THE INTIMATE STRUCTURE OF THE BRAIN. 
When paralysis of the facial nerve depends on central lesion it is frequently associated 
with paralysis of the abducens. Sometimes both nerves are paralyzed on one side, and 
one of them on the other ; and sometimes, but more rarely, both nerves are paralyzed 
on each side. I have seen two cases of this kind. One of them was in the practice of 
Dr. Hughlings Jackson. Now, when we consider that both the facial and abducens 
nerves are connected with the same nucleus on each side of the floor of the fourth ven- 
tricle (see fig. 51, Plate XIII. and fig. 65, Plate XIV.), it is evident that a tumour pressing 
on this part, or any morbid process that injured it, would paralyze at the same time both 
the facial and abducens nerves ; and if the lesion or foreign body extended across the ven- 
tricle to the other side, a bilateral paralysis to a greater or less extent would be the result. 
Dr. Wilks had under his care a little girl four years old, with paralysis of the right facial 
nerve and of both sixth nerves. The child’s arms and legs did not appear to be much 
affected, but the left arm and leg were a little weaker than the right. On post-mortem 
examination by Dr. Wilks, a tumour about the size of a large walnut was found to 
occupy the pons Varolii, and more on the right side than the left. On opening the 
fourth ventricle, the tumour was seen to project into its cavity, and thus all natural 
appearance of this part was gone. 
(88) I might dwell upon other points in this paper that may serve the purpose of the 
physiologist and pathologist, and which will probably be noticed by the reader, but I 
shall now conclude with a few words on the importance of combining together anatomy, 
experiment, and pathology in physiological investigations. A great physiologist, who 
conducted a large number of his researches by means of experiment, at length arrived at 
the conclusion, which he expressed in a paper read before the Royal Society, that anatomy 
is better adapted for discovery than experiment. “ Experiment,” he observes, “ may 
take a colour from the preconceived idea, but the accurate investigation of the structure 
will not deceive us”*. The truth, however, appears to be, that anatomy and pathology, 
no less than experiment, are liable to deceive, and that neither of them, alone, is suffi- 
cient for the purposes of the physiologist. In attempting to determine the function of 
a particular part, pathology must be employed with great caution, when other parts of 
the same complex organ are at the same time affected by disease. The many contra- 
dictory results obtained by different experimentalists on the same subject are so frequent 
that this method of investigation cannot be trusted alone. But experiment will be 
more accurate and precise just in proportion to the accuracy of our knowledge with 
regard to the structure and relations of the parts on which the experiments are made. 
Moreover, even if the anatomist cannot immediately draw any physiological conclusions 
from his observations, those observations may suggest and guide experiment ; and with 
this end in view, the philosophical observer will direct the course of his anatomical 
investigations. If, therefore, the experimentalist has made no original researches into 
the structure and relations of parts on which he purposes to operate, he must, if he 
wishes to avoid error, make himself thoroughly acquainted with the minute details of 
* Sir Chaeles Bell, Nervous System. 
