Genito - urinary organs. — Contractions of the ureters have been frequently observed by Valentin t to follow irritation of the abdo minal ganglia of the sympathetic. They pre sent the same peristaltic character as those of the intestines, and pass downwards from the kidney towards the bladder. In the bladder contractions are more easily pro duced than in the ureters: sometimes shortly after opening the abdominal cavity of an animal newly killed, the bladder contracts so powerfully as to give rise to an expulsion of its contents. Contractions may be excited in it, according to Valentin, by irritation ap plied to the sympathetic cord in the abdomen or pelvis, or to the lower lumbar and upper sacral ganglia ; the contraction commonly commencing on that side of the bladder on which the nerves have been irritated. The last lumbar and first sacral ganglia are de scribed by him as having most influence over its movements. In the vas deferens powerful contractions have been observed by Valentin when stimulus was applied to the two last lurn bar ganglia : the rabbit and guinea-pig were the anitnals on which this experiment was made. In the latter animal the vesiculm seminales were also excited to contraction by irritation applied to the lower lumbar and upper sacral portions of the sympathetic, sometimes so powerful as to expel the contents through the opening of the urethra. Stimulus ap plied to the same parts in the female gives rise to contractions in the Fallopian tubes. The uterus may, according to the same ob server, be excited to contraction by stimulus applied to the lower lumbar and upper sacral ganglia, or to the branches given off' from these. The contraction in such cases passes downwards from the Fallopian tubes towards the vag,ina.
In regard to the influence of the central parts of the nervous system over the move ments of these organs, it would appear, from Valentin's experiments, that contractions may be excited in the urinary bladder by stimulus applied to the spinal cord. The ureters are also said to exhibit contractions when the wires of the magneto-electric appa ratus are brought into contact with the me dulla oblongata, or with the spinal cord in the cervical or thoracic regions, as also when they are applied to the right optic thalamus. The same also holds true, according to him, regarding the vasa deferentia, Fallopian tubes, an] uterus. He has further observed, that often when the stimulus is applied to one side of the central nervous masses, it is the organ on the opposite side which is excited to contraction: thus stimulus applied to the right optic thalamus not unfrequently acts on the ureter of the left side ; in like manner, when the right hemisphere of the cerebellum is the part irritated the contractions some times take place in the Fallopian tubes or vas deferens of the left side.
These organs, however, like those already mentioned, exhibit their usual contractions after they are removed from the influence of the brain and spinal cord. The fact that in
paraplegic women delivery has taken place, would appear to show that the contractions of the uterus are not dependent upon the cen tral masses of the nervous system : this is also shown by an experiment of Segalas*, that di vision of the spinal cord in the lumbar region in the rabbit does not prevent the completion of the labour. Moreover, it would appear, from a series of experiments made by Pro fessor Simpson of Edinburgh, that the whole process of labour may be completed, although the spinal cord has, in great part, been pre viously removed.
Pupil. —lt was long ago ascertained by Pourfour du Petit t, that section of the main cord of the sympathetic in the neck is very quickly- followed by contraction of the pupil, besides certain other phenomena. The same experiment has since been made by Molinelli, Dupuy, Reid, Valentin, and others.t Molinelli regarded the effect pro duced upon the pupil not as an immediate effect of the operation, but as an after result; by Dupuy, on the other hand, it was de scribed as the immediate consequence of the same. Reid found in his experiments that the contraction of the pupil invariably takes place in the dog and cat, but in the rabbit the result is not so constant. Reid also showed that it was not the section of the trunk of the vagus, but that of the sympa thetic, that was the cause of the contracted state of the pupil. According to Valentin the effects produced differ considerably in different animals : in the dog the pupil be comes very much contracted : the contraction is not iminediate, but ensues within about half a minute after the nerve has been di vided. Stimulus applied to the nerve still causes the pupil to dilate, but in a few mi nutes it again contracts, until it is not larger than the head of a pin, and remains so for months. The contracted pupil has generally a circular form ; there are, however, occa sionally seen particular inequalities in its margin which change from time to time. When belladonna is applied the contracted pupil dilates, but does not reach the size which the sound pupil attains under similar circumstances. When the aqueous humour is tapped the contracted pupil becomes slightly widened, while at the same time it assumes a longish round forrn. In the sound eye when treated in this way the pupil be comes diminished in size.
Biffi found that slight dilatation of the pupil followed irritation of the ascending or carotid branches of the sympathetic, division of these being also followed by contraction of the pupil, though to a less extent than takes place after division of the sympathetic cord in the neck. Irritation of the superior cervical ganglion gives rise to the greatest dilatation of the pupil; so also when the same is extirpated the contraction of the pupil is very great.