The Microscope. 205 



examining attentively every part named, we discover "letails in 

 the structure which are truly wonderful. Good and typical cells,. 

 which Leydig already used for observation, may be found in 

 the epithelial lining of the intestines of the little crustacean 

 Oniscus murarius (pillbug or wood-louse). This animal is quite 

 common, gathering sometimes in great numbers under boards 

 placed along the foot of a wall. 



By magnifying these cells only about 260 diameters, and 

 properly staining them, the protoplasm is seen to be hyaline and 

 transparent, but is far from being homogeneous. In fact, fine 

 threads may be seen radiating from the nucleus towards the cell- 

 wall ; these threads send out lateral branches, which unite with 

 others so as to constitute a real network, which is technically 

 called the reticulum. The meshes formed by these interlacing 

 filaments are of various sizes and are filled with a hyaline, mi- 

 nutely granulated substance, which Professor Carnoy first (1883) 

 designated by the name of enchylema. 



Between the cells may be seen a shining zone, divided in the 

 middle by a dark line, the primitive membrane, common to jux- 

 taposed cells, as it is the result of cell-division, and at first con- 

 stitutes only a simple partition between the cells ; but sub- 

 sequently each cell constructs a wall for itself, and this secon- 

 dary membrane is the white shining lamella seen between the 

 cells. 



Next, by focussing upon the membrane of the cell, we may 

 see two things ; very minute points, caused, no doubt, by the 

 threads in the membrane crossing each other ; these belong ta 

 the primitive membrane, and the meshes they form are very 

 minute and hardly visible, but in the secondary membrane the 

 meshes are large and the threads clearly visible. We are there- 

 fore lead to the conclusion that the membrane also possesses a 

 reticulum and an enchylema, and is structured. 



Finally, within the protoplastic mass may be seen the nucleus, 

 shining like a beautiful pearl. In it may be seen trabeculse 

 crossing each other, constituting apparently a delicate network. 

 But this is a deception, for if accidentally the needle used in 

 dissection has drawn out a nucleus, we at once see that this is 

 not a real network, but that this filament is really a continuous 

 thread, and that it produced the appearance of a network owing 

 to its convolutions which cross and recross, the result being that 



