120 The Endocrine Organs 



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The blood-vessels are very numerous. There are no true nervous elements, 

 with the exception of a few fibres perhaps destined for the blood-vessels, 

 but neuroglia cells and fibres are present in abundance. Embedded both 

 in the interstitial tissue and in the covering of the pia mater are small 

 round globules of calcareous matter — corpora amylacea, brain sand — 

 which are much more common in man than in other animals, and more 

 numerous in the adult than in the child. The cells of the organ are not 

 uniform in character. Most have fine oxyphil granules in their protoplasm, 

 but some possess basiphil granules. Cells with large oxyphil granules such 

 as are seen in the anterior part of the pituitary are not found in the pineal. 

 Vesicles containing colloid are also absent, but cysts are not infrequent : 

 these may, however, be pathological. The gland undergoes retrogressive 

 changes after puberty : there is marked hypertrophy of the intertrabecular 

 tissue, which shows a characteristic reticular appearance resembling neuroglia 

 and at the same time considerable diminution in the number of epithelial 

 cells (fig. 84). 



Effects of Injecting Extracts of Pineal 



According to my own observations, extract of pineal injected intra- 

 venously produces a marked but temporary fall of blood-pressure accom- 

 panied by a diminution in volume of the kidney; the last is probably passive, 

 for no effect is manifest on the flow of urine (fig. 85). The substance which 

 produces these results is extracted from the gland by alcohol. 



Ott and Scott state that the result of intravenous injection of extract 

 of pineal is to produce a fall of blood-pressure followed by a prolonged 

 rise with dilatation of kidney volume and diuresis. They describe some 

 increase of contraction of the uterus. They also found a slight galacta- 

 gogue action. These effects are similar to those produced by pituitary 

 extract. They further obtained dilatation of the pupil on dropping the 

 extract into the eye of an animal in which the superior cervical ganglion 

 had been extirpated. Many of the above statements appear to require 

 confirmation, but the galactagogue action has been noticed by Mackenzie 

 (fig. 86). Previous workers, including Howell, Cyon, Dixon and Halliburton, 

 and Jordan and Eyster, have obtained no definite result from pineal ex- 

 tracts so far as arterial pressure and kidney secretion are concerned; if 

 we except the fall in blood-pressure, which Dixon and Halliburton consider 

 to be non-specific. 



Effects of Extirpation. Relations of the Pineal with the 



Sexual Glands 



Extirpation of the pineal is a difficult operation to carry through with- 

 out provoking severe haemorrhage, to which the animals operated on have 

 generally succumbed. The most complete series of experiments as yet 

 made are those of Foa on the domestic fowl, and those of Sarteschi on 



