The spider, as Isidore says in book 12 [Etymologies 12.5], is a worm of the air, named because of its subsistence from the air, which spins long threads from its small body, and being always intent on its web, it never relieves itself of its labor, and it sustains a continuous loss of its labor, because its web is often destroyed at a small breeze of wind or little drop of water from a rainshower, and then the spider totally re-creates its work. Avicenna, moreover, says that the spider is a little animal, a reptile, with multiple feet, having six or eight of them, which it always has in pairs,  and never in odd numbers, and this is necessary so that its walk can always be level, and so similarly the burden being carried, and this is a general quality in animals which have two or more feet.

It has however some feet which are longer, and some which are shorter, on account of the varied activities it undertakes. For with some of them it weaves its threads, and drags them long, but with some it ties its threads together, and with some it crawls across its threads, and when it wants, it hangs itself motionlessly on the top of the web.

original latin

Maxime autem inter animalia anulosi corporis viget in aranea sensus tactus. Unde residens in telae suae medio, subito sensit muscam telam in parte remotissima contingentem, quam subito invadit, et aggreditur tanquam hostem, de qua si triumphare potuerit, eam ne evadat, inter telae suae fila multipliciter circumvoluit, et primo capiti insidens eius humiditatem sugit, et de tali muscarum venatione vivit, nam eius gustabile proprie est talis humor, sicut gustabile apis est mel, sicut dicit idem Aristoteles.

Cuius videtur esse ratio, quia araneae et alia huiusmodi anulosa modici sunt nutrimenti, et parvi cibi, propter defectum sanguinis et caloris, unde cum aranea non tantum cibi capiat, quin incomparabiliter ad praeparationem telae continuae plus emittat, maior esse superflui emissio quam cibi sumptio, et maior est egestio superflua, quam digestio necessaria ad conservationem debitam animalis, ut dicit Aristoteles et Albertus.

Remedium autem contra morsus omnium aranearum est cerebrum gallinaceum cum exiguo piperis bibitum cum vino dulci. Item, coagulum agni potatum cum vino sanat morsus aranearum. Item facit cinis ungulae arietinae cum melle. Item, muscae contritae et positae super morsum extrahunt venenum et mitigant dolorem.