THE MINUTE ANATOMY OF THE LOCUST. 275 



The ridges all terminate just in front of the six large ridges or teeth 

 which mark the proventriculas. 



Dr. von Basch, in his treatise on the digestive tract of the Eastern 

 cockroach {Blatta orientalis);^^ considers the whole series of divisions 

 above mentioned to form collectively the anterior segment of the digest- 

 ive organs. This view is, however, probably erroneous, for reasons that 

 need not be detailed here. Professor Plateau has already shown that 

 active digestion begins in the crop. The mouth and oesophagus can 

 alone be considered merely as organs for the mechanical seizure and 

 preparation of the food. The blades of grass upon which the grass- 

 hopper feeds are cut up into small oblong pieces, which are further di- 

 vided in their passage through the oesophagus. But the chemical pro- 

 cesses of digestion begin even in the mouth, for the salivary glands 

 have their openings there, and their secretion has the power, according 

 to both Basch and Plateau, of converting into sugar the starch which, 

 green plants always contain so abundantly. It will thus be seen that, 

 strictly speaking, there is no part of the digestive canal which serves 

 solely to masticate the food, but it is nevertheless proper to call the oeso- 

 phagus and mouth the organs for the mechanical preparation of the 

 food, for their walls do not, as far as we know, contribute at all to the 

 digestive juices. 



Far different is the case with the crop, which performs a double func- 

 tion, for not only does it continue the mechanical division of the food, 

 but it also mixes it with an alkaline brown secretion, which it is sup- 

 posed is poured out by the glandular walls of the crop itself. At any 

 rate, the chemical changes in the food which render it suitable for ab- 

 sorption go on mainly in the crop, and not in the ventricle proper. 



The function of the proventricle {Kaumagen) is stated by P. Plateau, 

 and I think correctly, to have been misinterpreted by earlier writers, 

 inasmuch as it is not an organ of mastication, but really only a filter and 

 sort of valve, which allows the food to strain through when it has been 

 sufficiently triturated. 



The next division of the intestine is the stomach, or ventricle, which 

 has very delicate glandular walls. The true structure has not been fully 

 recognized by previous writers. It lies ventrally in the first to the fifth 

 abdominal segment ; it is nearly cylindrical, being somewhat enlarged 

 anteriorly to receive the opening of the proventricle and to connect with 

 the diverticula. In a median section, only one of these diverticula, or 

 blind pouches, appears, though there are several others which lie on 

 either side of the stomach. The shape and general anatomy of these 

 appendices have been described in detail by Dr. Packard. 1 will here 

 remark that they are decidedly different in their structure from the ven- 

 tricle itself, and they prepare, according to Prof. Felix Plateau,*' an 

 alkaline secretion. In transverse sections of the pouches, there appear 



"•fiSitzungsberichte der Wiener Akademie, sxxiii (1858), p. '234. 



4'Memoire3 do rAcadfimie dea Sciences, des Lettres et dea Beaux-Arts de Belgique, tome xU, 1875, 

 2"« m6moire. 



