The pineal body : a review / by Leonard J. Kidd.

  • Kidd, Leonard J.
Date:
[between 1910 and 1919?]
Catalogue details

Licence: Public Domain Mark

Credit: The pineal body : a review / by Leonard J. Kidd. Source: Wellcome Collection.

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    Further, it is of vital importance that we should learn what is the exact histological condition of the pineals of very old animals which had been castrated during the first few weeks of life. [My reason for insisting on this point will be given in my general discussion.] Finally, we want to know what effects, if any, has castration of very old animals on their pineal body. In concluding this section, I should like to express the hope that both the analytical and the physiological chemist will teach us some- thing of value on the obscure question of pineal chemistry: one cannot doubt that this method of inquiry has a future in front of it. 6. GENERAL DISCUSSION. We come now to the greatest difficulty of all—what use shall we make of the vast mass of facts which have been accumulated, as the results of the labours of numerous investigators in several fields of inquiry, during the modern era, which may conveniently be said to begin with the studies of Faivre? in 1854? First of all, a broad survey of the pineal body from all aspects leads, in my opinion, to one fundamental conclusion, viz., that it is probably functional in all those vertebrates which possess one. The pineal body is not, as so many even good authorities have assumed, a rudimentary, functionless, degenerated, or degenerating and disappearing organ. It is something entirely different, viz., a metamorphosed—perhaps also a metamorphosing—organ. If the pineal were really a degenerating and disappearing organ, Nature has been slow indeed in getting rid of it: she has had ever since the far-distant paleeozoic era. Let anyone just think of the fact that modern snakes, which are practically identical with those of the mesozoic era, have an unusually vascular pineal organ. Will he seriously ask us to believe that Nature would send a lot of blood to an organ that has no need for it, and thus keep a certain amount of blood from other organs and tissues which do need it? Now it does not in the least follow that, even if the pineal body be functional in all those vertebrates that possess one, its functions are of necessity identical in all vertebrate classes. We must here remember that we are to-day merely at the threshold of our inquiry into comparative pineal physiology. The alleged absence of a pineal organ in certain lower vertebrates is worthy of a passing notice here: its absence in Myxinoids is not in the least surprising ; for this group of the Cyclostomes is known to be—in the main—a very degenerate one. The absence of a pineal organ
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