789 



hereby rendered so thin that a break seems to have taken place 

 repeatedly. In the continuous series, iiovvever, we see distinctly 

 that there have been ruptures, the remains of which are frequently 

 to be seen, but where such is not the case or is doubtful, such 

 sections are followed by others in which the canal is closed. 

 The greatest depth of the ventriculus in this series is 0.670 mm. 

 and the maximum width is 0.250 mm., after which the canal grows 

 narrower. Although the walls are often irregular, distinct folds no 

 longer occnr. The ventriculus is aliout 4 mm. long. Even at the 



Fig. 15. Ovis aries 



Fig. 16. Sus scrofa domcsticiis 

 (foetus 3 mouths). 



end of the conns an occasional cell is to be found. Immediately 

 behind the end of the conus, beyond the continuation of the dura 

 lies a spinal ganglion which contains about 60 cells. In a longitu- 

 dinal section we see that the central canal itself is very irregular 

 in width, and that the folds are small and few in number. 



Sus scrofa domesticus (foetus of 3 months). This material 

 appears to have suffered greatly and only the series of the 

 last portion of the conns has been successful. At this place the 

 conus is f mm. in diameter, and round in section, the septum 

 posterius is not present and of the fissura anterior only a shallow 

 groove is left. No cells are to be observed. The canal no longer 

 lies in the centrum, it is a fairly narrow ellipsis in section, 0.3 mm. 

 deep and 0.07 mm. wide. Towards the back it Avidens 0.16 ram. 

 and the section becomes egg-shaped. On this level and also further 

 backwards we constantly find in the durapocket one or two spinal 

 ganglions of 0.250 mm. in diameter. The canal continues till it 

 strikes against the front and back walls of the conns (fig. 16), then 

 it widens in a ventral direction and ftnallj' decreases in width and 



