Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . tary state of invertebratephysiology, little can be certainly affirmed of thedigestive processes of any insect. The difficulties ofobservation and experiment are great, and the investi-gators are few. Plateaus memoirs on the physiology by him seemed to show that the saliva, as well asthe contents of the oesophagus and crop, had an acidreaction, while the contents of the chylific stomachwere neutral at the beginning of the tube and alkalinefurther down. From this he concluded that th
Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . tary state of invertebratephysiology, little can be certainly affirmed of thedigestive processes of any insect. The difficulties ofobservation and experiment are great, and the investi-gators are few. Plateaus memoirs on the physiology by him seemed to show that the saliva, as well asthe contents of the oesophagus and crop, had an acidreaction, while the contents of the chylific stomachwere neutral at the beginning of the tube and alkalinefurther down. From this he concluded that thedeep-seated glands of the chylific stomach secretedan alkaline fluid, which neutralised the acidity of thesaliva. Finding that the epithelial cells of thestomach were often loaded with oil-drops, he con-cluded that absorption, at least of fats, takes placehere. The chylific stomach, carefully emptied of itscontents, was found to convert starch into sugar atordinary temperatures. The saliva of the cockroachgave a similar result, and when a weak solution ofhydrochloric acid was added, Bascli thought that the. Fig. S4.^Salivary glands and receptacle of cockroach, right side. The arrow marks the opening of the common duct on the back oftheUngua. A, side view of lingua ; is, front view of hngua. of various Arthropoda are the most laborious andcomprehensive which we possess, f The observationsof Basch are earlier and less complete. Basch set out with a conviction that where achitinous lining is present, the epithelium of thealimentary canal secretes chitin only, and that properdigestive juices are only elaborated in the chylificstomach, or in the salivary glands. The tests applied * The contents of the malpighian tubules may be examined bycrushing the part in a drop of dilute acetic acid, or in dilute sul-phuric acid (lo per cent.). In the first case a cover-slip is placedon the fluid, and the crystals, which consist of oblique rhombohc-drons or derived forms, are usually at once ap
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