1902.] NATURAL SCIENCES OF PHILADELPHIA. 347 



esting, iu this couuectiou, to note that Krukeuburg (26) has fouud 

 a similar difference for Cavcinas mcenas. 



Huet has showu that the secretion of the hepatopancreas acts on 

 the proteids (muscular fibre and albuminoids generally, white of 

 egg, coagulated protoplasm of vegetable cells, etc.) iu Porcellio 

 scaber and hcvis ; on starch very slightly in the case of lAgia ; while 

 on fats he obtained only negative results (slightly emidsifies oil of 

 olives). He concludes that the secretion is " not a true bile." 



It has been seen in the section on the absorption of proteid that 

 albumose appears in the intestinal cells in eight hours (in one case 

 it was detected in four hours) after feeding. No attempt has been 

 made to establish ultra-minimum time for the appearance of dex- 

 trose in the intestine after feeding with starch. The least time 

 noted was twenty-four hours. There is good evidence that the 

 ' ' liver ' ' secretion accomplishes the hydi-olisis of fat. We may 

 conclude that the secretion of the hepatopancreas contains ferments 

 which act on all classes of foods. 



X. Summary and Conclusions. 



1. The apparatus concerned in the absorption of foods and the 

 production of secretion iu the land isopods consists essentially of 

 simple tubes, the intestine and hepatopancreas, bathed and separated 

 by the blood. 



2. That part of the intestinal wall concerned in absorption is a 

 single-layered epithelium composed of very large cells. That part 

 of the hepatopancreas concerned directly in the formation of secre- 

 tion is a single-layered epithelium, composed of smaller, young cells 

 and larger, maturing or matured cells. 



3. The intestine in the freshly hatched individual, a simple 

 tube, grows by amitosis, especially at the time of moulting, as well 

 as by enlargement of the cells. In tlie mid-dorsal line of the an- 

 terior portion a folding of the wall occurs later, giving rise to a 

 structure which we have called, after Couklin, the typhlosole. The 

 typhlosole arises in Porcellio spinicornis by a primary evagination 

 of the median six longitudinal rows of cells; there is then a sec- 

 ondary invagination of the median two rows, which project into the 

 lumeu and extend laterally by their free margin so as to cover the 

 lateral inner grooves formed at the sides, thereby cutting off, except 

 at the posterior end of the typhlosole, two channels, more or less 

 completely separated from the remainder of the lumen. 



