food, and that, when the outer coat is contracting, this air is easily forced with the food into the stomach, but that, when there only exists an inner coat, the air impedes the conveyance of food, by distending this coat and hindering its action. But Erasistratus said nothing about this, nor did he point out that the oblique situation of the gullet clearly confutes the teaching of those who hold that it is simply by virtue of the impulse from above that food which is swallowed reaches the stomach. The only correct thing he said was that many of the long-necked animals bend down to swallow. Hence, clearly, the observed fact does not show how we swallow but how we do not swallow. For from this observation it is clear that swallowing is not due merely to the impulse from above; it is yet, however, not clear whether it results from the food being attracted by the stomach, or conducted by the gullet. For our part, however, having enumerated all the different considerations--those based on the constitution of the organs, as well as those based on the other symptoms which, as just mentioned, occur both before and after the gullet has been exposed--we have thus sufficiently proved that the inner coat exists for the purpose of attraction and the outer for the purpose of propulsion. Now the original task we set before ourselves was to demonstrate that the _retentive_ faculty exists in every one of the organs, just as in the previous book we proved the existence of the _attractive_, and, over and above this, the _alterative_ faculty. Thus, in the natural course of our argument, we have demonstrated these four faculties existing in the stomach--the attractive faculty in connection with swallowing, the retentive with digestion, the expulsive with vomiting and with the descent of digested food into the small intestine--and digestion itself we have shown to be a process of _alteration_. VIII Epi men oun tês pepseôs, ei kai talla panta parelipe, to goun hoti diapherei tês ektos hepsêseôs hê en tois zôois pepsis, epeirathê deiknynai, peri de tês kataposeôs oud' achri tosoutou. ti gar phêsin? "Holkê men oun tês koilias oudemia phainetai einai." Kai mên dyo chitônas hê gastêr echei pantôs heneka tou gegonotas kai diêkousin houtoi mechri tou stomatos, ho men endon, hoios esti kata tên gastera, toioutos diamenôn, ho d' heteros epi to sarkôdesteron en tô stomachô trepomenos. hoti men oun enantias allêlais tas epibolas tôn inôn echousin hoi chitônes houtoi, to phainomenon auto martyrei. tinos d' heneka toioutoi gegonasin, Erasistratos men oud' epecheirêsen eipein, hêmeis d' eroumen.