THE PINEAL BODY 353 



beats continue after resection of the vagi. The results of these 

 experiments led v. Cyon to assume that it was the function of 

 the pineal gland to store up certain salts in organic combination ; 

 and that the physiological action of pineal extract is explained 

 by the presence of these salts, in comparatively large quantities, 

 both in the concretions in the spaces and distributed throughout 

 the tissue of the pineal gland. Calcium phosphate forms the 

 larger proportion of these salts. 



v. Cyon also describes the results of direct experimental 

 stimulation of the exposed pineal gland of rabbits. He found 

 that electric stimulation produced contraction, together with a 

 change in the length and the shape of the organ. He supposes 

 this contraction to be produced by the striated muscles, the 

 presence of which in the pineal gland of oxen and calves has 

 been proved histologically by Nicolas and Dimitrowa. According 

 to v. Cyon, a contraction combined with a shifting of the pineal 

 gland would regulate the in- and out-flow of the cerebro-spinal 

 fluid in the third ventricle. Thus the pineal gland would fulfil 

 the mechanical function of automatically controlling the flow of 

 the fluid in the aqueduct of Silvius, enlarging or reducing the 

 channel in accordance with the pressure in the third ventricle, 

 v. Cyon thinks that, like the thyroid gland and the hypophysis, 

 the pineal gland belongs to that group of organs which, acting 

 partly alone and partly in physiological concert, control inter- 

 cranial pressure. 



v. Cyon's experiments have not, as yet, been confirmed. As 

 far as the effect of pineal extract is concerned, Dixon and Halli- 

 burton (IQOQ) state that its intravenous injection is without 

 definite effect either upon blood-pressure or the cardiac contrac- 

 tions. The effect of pineal extract upon respiration, the intestines, 

 and the urinary secretion, is negative. 



Pathological Anatomy. Virchow was the first to draw atten- 

 tion to the pathological formation of cysts in the pineal gland. 

 Cysts have been recently described, the presence of which was 

 attended by no clinical signs whatever. In a number of in- 

 stances, serious pathological symptoms were present. 



Teratoid formations are of frequent occurrence in the pineal 

 gland. Since Weigert's classical description (1875), several 

 accounts of pineal teratoma have been given. Askanazy (1906) 

 regarded these formations as developments from a germ which 

 gained access to the pineal gland at the earliest stage of embryonal 

 life. Marburg believes the starting point of pineal teratoma to 

 be the primordial beginning of the parietal eye. In so far as the 

 clinical results are concerned, Askanazy supposes that these 

 tumours act like a foetus and produce certain anomalies of growth 

 to be described later. According to Marburg, these anomalies of 

 growth are the result of premature destruction of the active func- 

 tional pineal tissue. 



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