1. Deficiency And Excess Of Formation

We have already treated, in their connection with anomalies of the heart, of all anomalies or other defects of structure of the two arterial trunks, in so far as they present any true pathological interest. We would here only notice the following facts.

It is extremely doubtful whether there is a complete absence of a vascular system even in the most imperfect monsters, although extreme deficiency and a very imperfect indication of the two systems, is common in these cases. Where there is a deficiency of individual portions of the body there naturally exists some anomaly in the corresponding portions of the vascular system, which will present deficiencies corresponding in intensity to the degree, of arrest of development.

Supernumerary parts present a corresponding excess of formation in the vessels, although it must be observed that as a multiplication of organs is not uncommonly merely apparent, the multiplication of the arteries and veins implicated in the anomaly is only apparent, indicating the mere cleavage or subdivision of a trunk. We have already spoken, and purpose treating more fully, of the excess of vessels supplying different new formations. To these anomalies in the number of the individual vessels belong:

2. Anomalies In The Origin, Course, Etc, Of The Arteries

These, which are known as varieties, are very numerous, and are in part produced by anomalies of position and form in the corresponding organs. Several are highly important in reference to operative surgery; but as we are unable, from personal experience, to add any new facts in relation to this subject, we would refer our readers to the Monographs in which it has been treated, and to the ordinary Systems of Surgery.

3. Anomalies And Diseases Of Texture

We commence with the consideration of these anomalies, because they are both intrinsically important, and constitute the foundation of the principal consecutive anomalies and diseases, and because a knowledge of them is absolutely necessary for the right comprehension of the great majority and the most important of the alterations affecting the calibre and thickness of the walls of the arteries, their separations of continuity, and the subsequent phenomena to which they give rise. We shall institute various comparisons with the corresponding textural diseases of the veins, and we would here specially refer, on all these points, to the remarks we shall have to make subsequently on the diseases of the veins.