5. The superficial situation of the tendo Achillis, always renders the diagnosis of its division easy. It can be rendered difficult only by the occurrence of a considerable swelling, an accident that rarely happens. If there be an external wound, the depth to which the instrument has penetrated, and the possibility of sometimes feeling the ends of the tendon between the edges of the wound, are the first evidences of its division. If, on the other hand, the tendon be only ruptured, then at the moment when the rupture happens, a report is heard by the patient, not sharp, and like the crack of a whip, as is said to take place when the plantaris muscle is ruptured, but more dull and flat, according to the account given to Desault by a patient, whom he interrogated on the subject. 6. In either case, there occurs suddenly, if not an entire inability, at least, an extreme difficulty in either standing or walking: hence the patient falls, and is unable to rise again; but, in divisions that are only partial or incomplete (4), this sign does not occur. Between the divided ends of the tendon there exists a depression sensible to the touch. This depression is increased by the flexion of the foot, but diminished and even entirely removed by its extension. 7. The patient can spontaneously flex the foot, none of the flexor muscles being affected, and this flexion may be carried even beyond what is natural, because the divided tendon forms no obstacle to it behind. Spontaneous extension is also practicable, in as much as the peroneus longus, tibialis posticus, &c. which remain uninjured, are capable of producing that motion. Some have alleged that the calf of the leg must be increased in size by the swelling of the gastrocnemii and soleus muscles, in consequence of their state of contraction; but modern experience has shown, that there is but little reliance to be placed on that appearance. § III. OF THE PROGNOSIS. 8. Divisions of the tendons are not in general dangerous. These organs, being insensible in their nature, are not painful when ruptured, as is proved both by experiments on living animals, and by the observations of surgeons who have had such affections under their care, more particularly of Monro, who experienced the accident in his own person. No inflammation supervenes, and if a swelling be sometimes the consequence, it is in general soon dispersed, leaving behind it nothing serious.