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.
"Aphorisms and Reflections from the works of T. H. Huxley"
Thomas Henry Huxley
If these glands have the general form of tubes, they are called tubular glands; if sac-like in shape, they are called Saccular glands.
"Physiology and Hygiene for Secondary Schools"
Francis M. Walters, A.M.
This forms a compound gland which, depending on the structure of the minute parts, may be either a compound tubular or a compound Saccular gland.
"Physiology and Hygiene for Secondary Schools"
Francis M. Walters, A.M.