(55) 



the other parts of the brain I refer to my former paper (1902). 



I can only state here in reference to the contradictory statement 

 of Edinger, that even in more developed and in full-grown specimens 

 I never found another kind of cells in the organ nor an indentation 

 of the brainwall in front of the infundibular organ (Kupffer). In 

 fig. 1 is drawn a median section of the full-grown organ, and here 

 we see that the cells are not slanting any more, but are directed 

 perpendicularly to the longitudinal axis of (he body. In slightly 

 younger animals one often finds the greater part of the cell still 

 curved backward, while the upper part of the cell has assumed the 

 perpendicular direction already (fig. 4a). The cause of this change 

 must be sought in the different rate of growth of the surrounding 

 tissue, the whole cerebrum becoming shorter, and changing from an 

 oblong into a more rounded form. 



As I mentioned before, the cells of the infundibular organ have all 

 a backwards curved cilium; these cilia form a plume reaching to 

 the narrow part of the central canal. In young animals being examined 

 alive under the microscope the transparent tissue all round the brain 

 ventricle allows the course of these cilia to be very clearly visible, 

 and then the cilia of all the surrounding cells, pointing forward to 

 the anterior neuroporus, appear as straight hairs forming a compact 

 bundle which runs towards the neuropore, into which the hairs can 

 be traced as long as it is open. The back end of this bundle of 

 cilia is crossed by the cilia of the infundibular-cells. 



The form of the cells in the full-grown animal is shown in fig. 46. 

 The neurofibrillar differentiation in the protoplasm of the cell, as I 

 described it already in my former paper, the neurofibrillar network 

 round the nucleus and the way, in which the neurofibrilla leaves 

 the cell is in Fig. 3 clearly to be seen. The course of the nerve- 

 fibres after they left the cell-body I could not trace much farther 

 with a sufficient amount of certainty. They all seem to curve back- 

 wards (caudal), and from the study of frontal sections it was possible 

 to draw the conclusion that the nerve-fibres springing from the cells 

 form two bundles, each at one side of the median plane, running 

 backwards, but getting lost to view between the other fibres of the 

 medulla very soon after. 



I never succeeded in finding an indentation of the ventral cerebral 

 wall in front of the infundibular organ, as described by Kupffer, 

 although a large number of serial sections were examined. It is true! 

 that, as I mentioned before, often the nuclei in the ventral wall in 

 front of and behind the differentiated epithelium lie closer together 

 than in the other regions and in a few cases the arrangement of 



