[Illustration: Abdomen and leg, showing blood vessels, muscles and other internal organs.] Plate 33 PLATE 34.--The Internal Inguinal Hernia. The letters indicate the same parts as in Plate 33 [Illustration: Abdomen and leg, showing blood vessels, muscles and other internal organs.] Plate 34 COMMENTARY ON PLATES 35, 36, 37, & 38. THE DISTINCTIVE DIAGNOSIS BETWEEN EXTERNAL AND INTERNAL INGUINAL HERNIAE, THE TAXIS, THE SEAT OF STRICTURE, AND THE OPERATION. A comparison of the relative position of these two varieties of herniae is in ordinary cases the chief means by which we can determine their distinctive diagnosis; but oftentimes they are found to exhibit such an interchange of characters, that the name direct or oblique can no longer serve to distinguish between them. The nearer the one approaches the usual place of the other, the more likely are they to be mistaken the one for the other. An internal hernia may enter the inguinal canal, and become oblique; while an external hernia, though occupying the canal, may become direct. It is only when these herniae occur at the situations commonly described, and where they manifest their broadest contrast, that the following diagnostic signs can be observed. The external bubonocele, H, Plate 37, G, Plate 38, when recently formed, may be detected at a situation midway between the iliac and pubic spinous processes, where it has entered the internal ring. When the hernia extends itself from this part, its course will be obliquely inwards, corresponding with the direction of the inguinal canal. While it still occupies the canal without passing through the external ring, it is rendered obscure by the restraint of the external oblique tendon; but yet a degree of fulness may be felt in this situation. When the hernia has passed the external ring, T, Plate 36, it dilates considerably, and assumes the form of an oblong swelling, H, Plate 36, behind which the spermatic vessels are situated. When it has become scrotal, the cord will be found still on its posterior aspect, while the testicle itself occupies a situation directly below the swelling.