1889-90.] MORPHOLOGY AND PHYSIOLOGY OF THE CELL. 275 



Explanation of Plate I. 



The illustrations are drawn with the Abbe camera lucida, combined 

 with the 3mm. or the 2mm. apochromatic objectives (Zeiss), and compen- 

 sation ocular 4 or 8. 



Figs, i-ii are from the intestine oi Dieinyctylus viridescens. 



Fig. I. Three epithelial cells in each of which there are unusual struc- 

 tures — cp represents the cavity in which, apparently, a parasitic element 

 matured and whose spores are seen in the adjacent cytoplasm. In the 

 central cell are probably both spores and invaginated, cytolysed material, 

 while in the cell to the left there are structures which from their shape 

 appear to be parasitic. X720. 



Fig. 2. Two epithelial cells in one of which the nucleus is degenerated. 

 In both cells are seen structures exemplifying two stages in the develop- 

 ment of the same parasite. In the degenerated cell the parasite,/, is ma- 

 tured, but in the cytoplasm of the other cell, they are, apparently, all 

 comma-shaped. Xiooo. 



Fig. 3. A single epithelial cell containing a fairly typical specimen of 

 the parasite, n, the cellular nucleus, up, the nucleus of the parasitic organ- 

 ism. There is present a cavity and a rim of thickened protoplasm, /r. 



Fig. la. An epithelial cell in which the parasite, /, is in the stage of 

 transition from the comma to the adult form. Xiooo. 



Fig. 4. In this the parasite, p, possesses a central mass of protoplasm 

 in which is imbedded the nucleus and which sends processes toward the 

 periphery. The remains of the tail of the comma are still recognisable 

 in the denser portion of the periphery. X 1000. 



Figs. 5, 6, and 7. The sporulation stages of the parasite with the 

 trabecular arrangement of the cell protoplasm pc, well marked The 

 horseshoe form of the spore is clearly shown in 6a. X 1000. 6n. X2250. 



Fig. 8. Represents five stages in the development of the sporulation 

 phase of the parasite. In a the thickened band of protoplasm at one 

 side represents the remains of the tail of the comma stage ; in b the two 

 central rings probably represent a stage of mitosis which is further ad- 

 vanced in c ; 'vc\ d the spores are formed each in a cavity of the ptoor 

 plasm and these are further developed in e. Xiooo. 



