416 ME. H. M. BERNARD ON THE CHERNETID^. 



strongly reminded of fhe similar crystalline bodies found in 

 Amosbse. On referring the matter to my friend Mr, Moore, lie 

 informed me that he had himself come to the conclusion that the 

 so-called " crystals " of Amoebae are the indigestible remains of 

 food-globules, which in these animals also are almost indistin- 

 guishable from oil-drops. Mr. Moore's conclusions were already 

 in print*, otherwise this complete and unexpected confirmation 

 of them would no doubt have been mentioned. 



In one specimen, infected with bacteria, these large digesting 

 cells, while apparently retaining their purely digestive functions, 

 seem to be unable to get rid of the excreted matter which accu- 

 mulates between the cells, as shown in fig. 8. 



These simple conditions of the digestive processes in Oiisitim 

 are of great importance. They have enabled us to recognize 

 the supposed secretions of the " liver " cells of the Arachnids as 

 no true secretions, but as homogeneous food-globules, and the 

 various forms of "crystals" found in the cells as the fsecal 

 remains of these food-globules. It follows, therefore, that the 

 whole subject of the digestion of the Arachnids, so ably worked 

 out by Plateau t and Bertkau J from the old point of view, 

 should be restated from the new point of view above described, 

 that the cells lining the diverticula of the alimentary canal are 

 not glandular cells filled with their secretions, but digesting 

 cells whose contents are to be referred to food in various stages 

 of digestion. I have endeavoured to follow up this subject in a 

 paper read before the Eoyal Microscopical Society and since 

 published in that Society's Journal (Aug. 1893). 



Outside the basement-membrane of the digesting epithelium 

 is a layer of single cells homologous with the " fat body," 

 described by Bertkau as occurring between the "hepatic " diverti- 

 cula of the Araneids. These peritoneal cells vary considerably 

 in shape, in some places being almost tile-shaped, and in others 

 long and cylindrical. This latter form is sometimes found when 

 thesB cells form part of the boundary of a blood-sinus, where 

 they are free to develop. In places, on the other baud, where 

 they are liable to be squeezed between adjacent parts of the 



* Ann. & Mag. N. H., Feb. 1893. 



i" " Eecherckes sur la structure de I'appareil digestif et sur les phenomenes 

 de la digestion chez les Aran^ides dipneumoues," Bulletin de I'Acad. Koyale 

 de Bruxelles, 2*^ Serie, torn. 44 (1877). 



: L. c. p. 4l4. 



