CERATOMYXA ACADIENSIS. 



565 



have moved in opposite directions along the antero-posterior axes of 

 their respective spores. 



A similar state of afYairs is seen in the slightly more advanced sporo- 

 blasts shown in Figure 39 (PI. II). The nuclei of the valve-cells show 

 the same condition as that in the stage last described. The regular 

 arrangement of the granules at the periphery of the nucleus suggests 

 the presence of a nuclear membrane, and in some cases a faint sugges- 

 tion of such a structure is to be seen as a continuation of the contour 

 of the nucleus between the principal granules (PI. II, Fig. 39, upper 

 left hand nucleus). The changes in the nuclei of the valve-cells fol- 

 low closely those described for the nuclei of the valve-cells of Sphaer- 

 omyxa sabrazesi by Schroder (:07, p. 368), who writes: "Die 

 Schalenkerne werden etwas grosser, langlich und flach; ihr Chromatin 

 sammelt sich mehr und mehr unter der Kernmembran an." In the 

 right hand sporoblast of Figure 39 (PI. II), at the lower end of the 

 figure, a little above the nucleus of the valve-cell, may be seen a faint 

 transverse line, which probably marks the internal boundary of the 

 valve-cell; this line is also to be seen in later stages (cf. PI. II, Fig. 40, 

 upper end of spore). 



cps. pol. 



fill kit. 



Figure A. Ceratomyxa acadiensis, n. sp., spore drawn from a fresh 

 preparation to show method of orientation and the form; a., anterior margin; 

 p., posterior margin; s., left valve; dx., right valve; cps. j)ol., polar capsule; 

 fil. lat., lateral filament. X 1800 diameters. 



A considerably later stage in the development of the spore, still in 

 the gall bladder, is shown in Figure 40 (PI. II). The sporoblast has 

 now become a spore. The valve-cells extend out in a lateral direction 

 on either side. They are shaped like a cone with a cavity which ex- 

 tends about half way towards its apex. The nuclei of the valve-cells 

 stain \ery faintly, only one or two faint granules showing at the 

 periphery, the greater part of the chromatic substance having dis- 

 appeared. The nuclei of the capsulogenous cells also have shrunk 

 somewhat and one of them, the lower in the Figure, is divided into two 

 parts. The chromatin substance is still peripheral in position, but 



