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Updated: May 18, 2025
B. Simple tubular gland. C. Simple saccular gland. D. Compound tubular gland. E. Compound saccular gland. F. A compound racemose gland with duct passing to a free surface. G. Relation of food canal to different forms of glands. The serous coat has a secreting surface.
What are the parts common to all glands? What purpose is served by each of these parts? How do tubular glands differ in structure from saccular glands? What is a racemose gland? Why so called? Describe the nature of the secretory process. What conditions render necessary the formation of waste materials in the body? Why must these be removed?
Experience has shown that this method possesses great advantages, and that it has none of the disadvantages which were formerly supposed to attend it. Saccular dilatations of arteries which are the result of cuts or other injuries are treated by tying the vessel above and below, and by dissecting out the aneurysm.
And if, as I believe, it can be demonstrated that ordinary coal is nothing but "saccular" coal which has undergone a certain amount of that alteration which, if continued, would convert it into anthracite; then, the conclusion is obvious, that the great mass of the coal we burn is the result of the accumulation of the spores and spore-cases of plants, other parts of which have furnished the carbonized stems and the mineral charcoal, or have left their impressions on the surfaces of the layer.
In those aneurysms which are a saccular bulging on one side of the artery the blood may be induced to coagulate, or may of itself deposit layer upon layer of pale clot, until the sac is obliterated.
A blood cyst or hæmatoma results from the encapsulation of extravasated blood in the tissues, from hæmorrhage taking place into a preformed cyst, or from the saccular pouching of a varicose vein. A lymph cyst usually results from a contusion in which the skin is forcibly displaced from the subjacent tissues, and lymph vessels are thereby torn across.
But what I may term the "saccular matter" of the coal, which, either in its primary or in its degraded form constitutes by far the greater part of all the bituminous coals I have examined, is certainly not mineral charcoal; nor is its structure that of any stem or leaf. Hence its real nature is at first by no means apparent, and has been the subject of much discussion.
Again, the late Professor Quekett was one of the first observers who gave a correct description of what I have termed the "saccular" structure of coal; and, rightly perceiving that this structure was something quite different from that of any known plant, he imagined that it proceeded from some extinct vegetable organism which was peculiarly abundant amongst the coal-forming plants.
And if, as I believe, it can be demonstrated that ordinary coal is nothing but "saccular" coal which has undergone a certain amount of that alteration which, if continued, would convert it into anthracite; then, the conclusion is obvious, that the great mass of the coal we burn is the result of the accumulation of the spores and spore-cases of plants, other parts of which have furnished the carbonized stems and the mineral charcoal, or have left their impressions on the surfaces of the layer.
If these glands have the general form of tubes, they are called tubular glands; if sac-like in shape, they are called saccular glands. Both the tubular and the saccular glands may, by branching, form a great number of similar divisions which are connected with one another, and which communicate by a common opening with the place where the secretion is used.
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