Reviews

1912 BMJ (Clinical Research Edition)  
book on the physiological imiiportance of thyroid, pituitary, pineal, and suprarenal glands' which he dedicates' to his old master in physiology, Edward Pfluiger. The work commences with a prefatory chapter on the heart, the ear labyrintl, and hypophysis. The author then describes the details of a series of experiments carried out by him on the horse," dog, and rabbit to'determin'e the function of the thyroid, pituita'ry, pineal, and suprarenal glan'ds. These experinents were of a twofold
more » ... . First, he injected into the vena jugularis a solution in glycerine or water of the active substance of the gland in question. Secondly, he exposed the gland and subjected it to mechanical pressure and electrical stimulus, noting carefully in each case the symptoms arising from such treatment and recording tracings of the pulse. Compression of the aorta was another method used to excite the gland. In the case of the suprarenal the experiments were limited to. the injections. His conclusions are as follows: 1. The thyroid gland has a chemical as well as a mechanical function. (a) It manufactures a substance (iodothyrin) wllich controls the nervous apparatus regulating the heart, and also, when present in the circulation, has the pow'er of eliminating various substances from the organism which have a deleterious effect on the nervous system. (b) The thyroid can also act as a protector against congestion of the brain in cases of suddenly increased activity of the heart or sudden contraction of the peripheral' vessels. This power is due to its large vascular capacity, which permits it to control, to some extent, the circulation of the blood to the, brain. lodothyrin counteracts the paralysing effects of atropin and nicotin on the vagus. 2. The pituitary gland also acts mechanically and chemically. It is an autoregulator of the intracranial blood pressure, and acts in conjunction with the thyroid in guarding the brain against undue congestion. The glandular portion of the pituitary manufactures two substances, the most important of which the writer has named "hypophysin." This substance has the power of increasing the action of the heart. The injection of pituitary extract into the vein caused a diminution of pulse-rate with an increase of strength. At the same time the blood pressure rose. This condition would sometimes last for hours. This view regarding the blood pressure would seem to coincide with Schafer's later views, but the author thinks that Schafer has missed the important action of hypophysin in slowing the pulse-rate and increasing its strength. Schafer's latest work on the subject of this gland, published in Bern, was written before he saw von Cyon's book. Hypophysin is also a powerful antagonizer to the action of atropin and nicotin on the vagus. It has not,however, the power of counteracting an already existing vagus paralysis caused by these drugs. Probably it can also protect the organism from poisonous products formed in the svstem. By means 8f its chemical activity, thepituitary regulates not only the sympathetic and vagus systems, but also the metabolism of'thb tissues and glandular secretion.' Further, it influences powerfully the development and growth of the tissues, especially the osseous system. Destruction or removal of' the gland means death to the individual. 3. The pineal gland acts for the most part mechanically only, andregulates the cerebro-spinal fluid flowina to' and from the aqueductus Sylvii. To this'end it works in conjunction' with the" pituitary. A'very slight electrical stimulus' caused the pineal gland to contract visibly without appearing paler incolour, so that the diminished size woulld not seem to be due to the contraction of blood vessels. The author ascribes it'rather to thee presence of striated muscle fibr6s in the'gland, w-hich he' and others have observed. He noticed that these fibres were arranged in like manner to those of the heart. 4. Suprarenal gland. The injection into the vein of tlle active substance of this glaild produced a marked excitation of the sympath'etics of the heart and vascular system (accelerantes and v'aso-constrictores), and paraly-sed the vagus and depressor: it must therefore be considered as antagonistic to iodothyrin and hypophysin. There was an enormous rise in the blood pressure, which von Cyon attributes to an excitation of the whole va'so-constrictor nervous system belonging to th'e cerebral centres' as well as of the ganglia of the rest of the vascular system. This is in contradistinction to Schafer and 'Oliv'er's view that it iscaused by direct stimulus of the muscle's of the heart and arteries.
doi:10.1136/bmj.1.2673.676 fatcat:w2uvpd4a7ng55ei7ei7zm3i2tq