PINEAL BODY 389 



pressure. Cyon concludes that these effects are due to the 

 calcium phosphate and other salts from the concretions of the 

 gland. 



Dixon and Halliburton find, as might have been expected, 

 that extracts of the pineal body, when intravenously injected, 

 give a fall of blood-pressure (see Chapter III.). Extracts 

 of the choroid plexus also bring about a lowering of the blood 

 pressure. They find also that while extracts made from the 

 choroid plexus of the ox, sheep, and man, injected into the 

 sub-cerebellar cisterna, or the lumbar region, cause a flow of 

 cerebro -spinal fluid, extracts of pineal body have no such 

 effect. 



Ott and Scott report, in addition to some changes in the 

 blood-pressure, that pineal intravenous injection has a galacta- 

 gogue action similar to, though less than, that of pituitary 

 extract (see p. 353). 



Jordan and Eyster in 1911 found on pineal injection a 

 vasodilation in the intestines, a more forcible beat of the 

 isolated cat's heart, diuresis and glycosuria. There was also 

 increased depth of breathing for some time after the injection. 

 The effects are comparatively slight. 



Schafer andMacKenzie (see Chapter XV.) could not confirm 

 the observation of Ott and Scott as to the galactagogue action 

 of pineal extracts. But MacKenzie in 1911 obtained a slight 

 effect which he thought might be due to contamination with 

 pituitary material by absorption from the cerebro -spinal fluid. 



2. Direct Stimulation of the Pineal Body 

 Cyon appears to be the only observer who has used this 

 method. He employed electrical stimulation applied to the 

 pineal body of the rabbit and states that he could observe 

 slight changes in the form and position of the gland. There 

 was no alteration in colour, so that the effects could not be due 

 to vasoconstriction. They were due, he thinks, to con- 

 traction of muscle, though, it must be observed, the existence 

 of muscle fibres in the body is exceedingly doubtful. According 

 to Cyon, these experiments point to a mechanical function on 

 the part of the pineal body : it is suggested that it controls 

 the inflow and outflow of cerebro -spinal fluid of the third 

 ventricle. The part played by the pineal body in this regard 

 is likened to that of the thyroid and the pituitary, and aU three 



