CERATOMYXA ACADIENSIS. 563 



Figures 21 and 22 (PI. I), different views of the same sporoblast, 

 show a sHghtly more advanced stage than the previous one. The 

 nuclei of the valve-cells and the nuclei of the capsulogenous cells 

 have increased slightly in size and the chromatin is nearly all at the 

 periphery of the nuclei. The polar capsules have begun to develop, 

 as is to be seen by the presence of two clear areas, each containing a 

 stained central mass. In preparations stained with Heidenhain's iron 

 haematoxylin there is an evident connection of this mass with the 

 protoplasm forming the periphery of the clear area. It would there- 

 fore seem that the polar filament is developed from a club-shaped 

 mass of protoplasm, which grows out into the vacuole which ulti- 

 mately forms the cavity of the capsule. It may, therefore, be that 

 the polar filaments, like the valves of the spore envelope, are formed 

 from metamorphosed protoplasm. The comparison can be carried 

 further, as it is found that the filaments, the walls of the capsules and 

 the valves of the spore-shell form continuous structures, which ad- 

 here when the two valves are separated and the other parts of the 

 spore have disappeared. 



The stage in the development of the polar filament described above 

 resembles the stage found in Sphaeromyxa sabrazesi Laveran et 

 Mesnil by Schroder, that formed in Myxobolus pfeifferi Th. by Keys- 

 selitz (:08) and that in Zschokkella hildae Auerb., by Auerbach (:09). 

 Any connection of the nucleus with the formation of the vacuole, 

 such as Awerinzew has described for Ceratomyxa drepanopsettae 

 Awer., I have not observed. 



A myxosporidium containing two sporo blasts at a slightly more 

 advanced stage than that represented in Figures 21 and 22 (PI. II) 

 is shown in Figure 28. The separate sporoblasts are represented in 

 Figures 26, 27, 29, 30. Here the sporoblasts have elongated without 

 increasing greatly in size and their long axes are becoming curved. 

 The nuclei of the cells which form the valves show the chromatin at 

 the periphery and a clear interior. The nuclei of the capsulogenous 

 cells are approaching this condition. The nuclei of the sporoplasm 

 show the same condition as in the previous figures. 



A somewhat older stage is shown in Figures 31-34, which represent, 

 in the same way as Figures 26-30, a myxosporidium containing two 

 sporoblasts. Each sporoblast has increased considerably in size and 

 shows a greater curvature of its long axis. The sporoblasts are so 

 placed that their concave surfaces are in contact, and they lie usually 

 with their bivalve axes ^ parallel, and therefore so that one sporoblast 



8 8ee page 566. 



