Arborescent Form Research Articles

Aralia in American Paleobotany

IN a study of the mid-Cretaceous floras of the Atlantic coastal plain, the difficulty of determining by what characters certain leaves were allied to Aralia, Sassafras, or Sterculia led to a somewhat extended review of these genera, more particularly the former, which is so abundantly represented throughout the American Cretaceous and Tertiary. As to the relationship of these leaves with modern species of Aralia, we are not here especially concerned. Leaves of this type, however, are such a constant feature of these ancient floras, both in this country and abroad, that they possess an unusual degree of interest, and I have endeavored in the following notes to define more precisely the characters which serve to distinguish these leaves from leaves of other genera with which they are often confused. The existing species of Araliaceae number about 450, which Harms, in Die naturlichen Pflanzenfamilien, distributes among 5I genera. They are widely distributed in the temperate and tropical regions throughout the world, and include herbs, shrubs, and trees with simple, lobed, or compound leaves. The genus Aralia, as restricted, includes some 27 species of North America and Asia with ternately and pinnately decompound leaves. The only fossil form which seems to stand in this ancestral line is Aralia triloba Newb. from the Fort Union Tertiary. In North America north of Mexico we have six existing species of Aralia, four eastern and two western (besides three varieties). Of these Aralia spinosa L. is the only arborescent form. Beside Aralia two other genera occur with us: Panax, with two eastern North American species and five species of central and eastern Asia; and Echinopanax, with one species on the Pacific coast of America, which reappears in Japan. Many other genera occur in the West Indies, Mexico, Central and South America.

Account of a peculiarity in the distribution of the arteries sent to the limbs of slow-moving animals; together with some other similar facts. In a letter from Mr. Anthony Carlisle, Surgeon, to John Symmons, Esq. F. R. S

This peculiarity was first observed in the axillary arteries and in the iliacs of the Lemur tardigradus, which at their entrance into the upper and lower limbs were found to be suddenly divided into a considerable number of equal-sized cylinders, which occasionally anastomosed with each other, and were regularly distributed on the muscles; whilst the arteries proceeding to the other parts of the body divided in the usual arborescent form. Upon prosecuting this inquiry, it was found that the Bradypus tridactylus, and in some measure also the didactylus, has a similar distribution of these arteries.

VI. Account of a peculiarity in the distribution of the arteries sent to the limbs of slow-moving animals; together with some other similar facts. In a letter from Mr. Anthony Carlisle, surgeon, to John Symmons, Esq. F. R. S

Dear Sir, The Maucauco you have been so obliging as to give me for the purpose of dissection, has proved a subject of considerable interest. This animal, the Lemur tardigradus of Linnæus, was injected, with a view to exhibit the course of the arteries; and they present a very unusual deviation from the ordinary arrange­ment of this class of blood-vessels in animals generally. Before I had leisure to inquire further into this peculiarity, I presented a drawing of the appearances to my friend Dr. Shaw, of the British Museum, for the purpose of being made public in his work of natural history, now in the press. Since that time, I have, through Dr. Shaw’s assistance, been enabled to investi­gate this subject somewhat farther; and, if you consider the following account in any degree worthy the attention of the Royal Society, I shall receive an additional honour by its pro­ceeding through your hands. The Lemur tardigradus , in its injected state, accompanies this paper; and, for the kind of preparation, the vessels are filled with more than ordinary success. The arteries alone are injected; and the peculiarity of their arrangement is to be observed in the axillary arteries, and in the iliacs. These vessels, at their entrance into the upper and lower limbs, are suddenly divided into a number of equal-sized cylinders, which occasionally anastomose with each other. They are exclusively distributed on the muscles; whilst the arteries sent to all the parts of the body, excepting the limbs, divide in the usual arborescent form; and, even those arteries of the limbs which are employed upon substances not muscular, branch off like the common blood-­vessels. I counted twenty-three of these cylinders, parallel to each other, about the middle of the upper arm; and seventeen in the inguinal fasciculus.