178 J. J. LISTER. 



disposition suggests that they have been set free by the breaking up of a 

 compound nucleus. Optical section. Picro-carmine. 



Fig. 22. X 1460. Part of a section of a nucleus whose nucleoli contain 

 many vacuoles. 



Fig. 23. X 250. Specimen with a "flushed" region of the protoplasm 

 at one end of the nucleus, due to the presence of minute stained particles. 

 Picro-carmine. 



Fig. 24. X 250. Specimen showing "fragments" lying in the cham- 

 bers through which the nucleus has passed, and in those immediately 

 beyond it. In this figure the fragments have been somewhat over- 

 emphasized, they are generally much less conspicuous. 



Fig. 25. X 1460. Sections through such fragments as those shown in 

 fig. 24. In this case they contain nucleoli, a and h are consecutive 

 sections of the same fragment. Picro-carmine, hcematoxylin. 



Fig. 26. X 230. A nucleus which has lost its rounded form. 



Fig. 27. X 250. The whole of the protoplasm, except that occupying 

 the last two chambers, has broken up into small nucleated spheres, having 

 a diameter of 2'5 to 3 fi. At c, a portion of the spiral canal, which lies in 

 the umbilical region, is seen filled with similar spheres. Picro-carmine. 



Fig. 28. X 1275. Part of a section of the same specimen as that in 

 fig. 27. The nuclei which lie in the spheres are seen to be in process of 

 karyoldnetic division. Picro-carmine and hsematoxylin. 



Fig. 29. X 487. Section of nucleus with few and irregularly outlined 

 nucleoli. Flemming's fluid. Safranin. 



Fig. 30. X 730. Section of the terminal chamber of a specimen of 

 the megalospheric form, in which the large nucleus has disappeared, and 

 numbers of small nuclei 1 to 1'5/i in diameter are distributed in groups 

 through the protoplasm. Picro-carmine and hsematoxylin. 



Fig. 31. Part of a section through a specimen of the megalospheric 

 form, in which the large nucleus has disappeared and numbers of small 

 vacuolated nuclei are distributed through the protoplasm. The structure 

 of the protoplasm is not represented. Zeiss ^ oil. 



Fig. 32a. X 460. Section of a specimen of the megalospheric form in 

 which the whole protoplasm is broken up into zoospores, having a diameter 

 of 3 to 4^. A broad communication is seen to connect chambers 2 

 and 10. 



Fig. 326. X 1460. Groups of zoospores in the terminal chambers ; 

 indications of flagella are seen. In the left-hand group of zoospores the 

 nuclei have not taken the stain. 



Fig. 33a and h. x 1200. Actively moving bodies which emerged from 

 a specimen of Polystomella crispa. Probably they belonged to another 

 organism. 



