THE ANATOMY AND DEVELOPMENT OF PERIPATUS NOVAE-BRITANNIAE. 



27 



between the basal membrane and the cuticular membrane are stretched irregular 

 strands of protoplasm up the centre of which may often be traced a fine supporting 

 axis which perhaps represents a cell-membrane. The strands of protoplasm are beset 

 with innumerable eosinophile globules of varying sizes. The supporting axes mentioned 



Fig. 5. Portion of the endoderm of P. novae-britanniae at stage x. 

 The coarsely granular endoderm-cells or trophocytes lie upon the membrana propria projecting freely into 

 the trophic cavity. The cells are often separated by wide intervals. 



above, which stretch from membrane to membrane, obviously serve the purpose of 

 holding the granules in position and, on the other hand, the cuticular membrane 

 which is a temporary structure and not always if ever present in the adult, serves 

 the purpose of providing a point d'appui for the strands of protoplasm with their 

 globules. The nuclei lie near the base of this thickened epithelium. 





Fig. G. PORTION of the wall of the mid-gut of P. novae-britanniae at stage xi. 



The endoderm has become a thickened compact layer containing numerous eosinophile globules. The 



cuticle at the inner surface of the endoderm has become (artificially) separated at this point from the cells 



which secreted it, this portion of the section having been selected for representation in order to show the 



membrane as a distinct cuticular product. The protoplasmic matrix of the globules is not shown in the figure. 



In Stage XII this remarkable epithelium (which has meanwhile still further in- 

 creased in thickness) with its contained eosinophile globules is, in my preparations, 

 in process of undergoing complete disintegration. The cuticle is ruptured locally and 

 the globules are passing singly and en masse into the gastral cavity presumably 

 preparatory to their resorption. In other words, the wall of the gastral cavity is 

 undergoing a histolytic change and the scene presented while it is doing this, is one 

 of the utmost disorder 1 . In this stage the globules average larger and are somewhat 

 less numerous than in the preceding stage. 



These globules are clearly the product of the metabolism of the endoderm cells 

 which have converted the nutrient matter derived from the maternal fluids into 

 i This is true of the posterior region of the particular embryo referred to. In the anterior region the 

 changes are far less advanced although there are indications of their approach. 



4—2 



