The _vibratory_ derives its name from an imaginary resemblance to the motions of a rod or dart when thrown into the air, and it can only take place when the artery is hard, and the strength good. Le Clerc renders it _le pouls dardant_. It is generally named _thrilling_ in modern works. According to Actuarius, it is hard, quick, and dense, and indicates inflammation of nervous parts. The _undulatory_ derives its name from a supposed resemblance to the rolling of the waves, and can only take place when the artery is particularly soft, being accompanied with an unequal elevation of it in the diastole. It is thus described by Rhases: “Undosus vero est qui secundum latitudinem, magnum digiti occupat locum, cum lenitate et repletione, cum eo tamen non est magna elevatio neque subita, sed videtur quod elevationem ejus una post aliam contingit, donec fit ut undis assimilatur, quarum una aliam sequitur.” It is the _pulsus fluctuosus_ of Haly Abbas, and the _pulsus fluens_ of C. Aurelianus. (Morb. Acut. ii, 32.) Le Clerc renders it _ondoyant_. The _vermicular_ differs from the last mentioned only in magnitude and strength, being soft, small, and weak. Nearly allied to it is the _formicans_ or _ant-like_ pulse, which is one of the last degree of weakness, smallness, and density. They are thus described by Rhases: “Vermicolosi forma est ut forma undosi, in elevatione quæ secundum diastolem eadem invenitur, non tamen est latus, neque plenus, cujus inundatio existit debilis, qui vermibus per foramen arteriæ discurrentibus assimulatur: formicans vero pulsus adeo invenitur in ultimo parvitatis, et spissitudinis consistere, ut pulsui pueri recens nati assimuletur.” According to Galen the _formicans_ is a pulse which it requires great experience to detect. (De Dignos. Puls. ii, 1.) Haly Abbas states that it is the termination of the vermicular. It is the _pulsus formicabilis_ of Cælius Aurelianus. The Chinese compare the formicans to a silk thread, a capillary tube, or a hair. The _intermittent_ and _intercurrent_ pulses are opposed to one another, there being a complete failure of a pulsation in the one case, and an accessory or superfluous one in the other. There cannot be a better proof of the imperfection in our modern systems of the pulse, than that there should be no mention in them of the intercurrent pulse. The _hectic_ pulse, it is well known, is small and dense. Alexander Trallian says, small and feeble. (xii, 4.) The _serrated_ is hard, quick, and unequal in its feel. Rhases says that it is principally observed in inflammations of the pleura and diaphragm. According to Actuarius, the pulse characteristic of inflammation is serrated and hard, more especially if seated in a tendinous part. (Meth. Med. i, 25.) Le Clerc renders it _le pouls en manière de scie_. (Hist. de la Méd. p. iii, l. iii, c. 3.) It appears to correspond with the pulse called _harsh_ in the works of English writers on medicine.