Z00L03Y AND BOTANY, MIROSCOPY, ETC. 
579 
agree with those of Klein and Flemming, we come to Butschli’s foam 
theory. Flemming criticises severely Butschli’s methods, and believes 
that the greater part of his observations are based on material greatly 
modified by the reagents used, and that therefore most of his conclu- 
sions are unreliable. In cells where the protoplasm is clearly vacuo- 
lated, careful observation shows that the intermediate walls do not 
consist of homogeneous substance only, but of a mixture of this and 
fibrillae. Flemming then touches lightly on Altmann’s granule hypo- 
thesis, which he rejects, and on the views of Reinke and Waldeyer, 
which he regards as an attempt to reconcile the granular and the 
fibrillar theories. Flemming himself sees in the cell only the fibrillar 
framework and the interfibrillar substance, and is unable to further 
analyse either. The address was illustrated by preparations which are 
described. 
Prof. His,* in a discussion of the paper, touches upon some points 
not treated of by Prof. Flemming. First as to the cell-periphery. 
The cell is surrounded by a peripheral layer of morphoplasm (fibrillar 
substance), and when this is absent the cells form a syncytium. His 
believes that the morphoplasm is the active substance, and the hyalo- 
plasm a tenacious fluid. 
Optic Chiasma of Amphibians.j — Herr Franz Fritz has applied 
modern histological methods to the study of this structure in various 
Antira and TJrodela. He finds that the crossing is total, and where the 
nerves cross they break up into numerous small bundles of fibrils which 
form an interlacing basketwork. The same condition exists in Mam- 
mals, Ganoids, and Selachians. It does not occur in Teleosteans, and 
curiously enough is also absent in certain birds (e.g. the owl). This 
last fact is against the usual assertion that the Teleostean condition is 
primitive. Probably the two conditions have each their special signific- 
ance, but what this is it seems impossible at present to explain. 
Structure of Cerebellum. :£ — Herr Alfred Shapfer has undertaken a 
series of investigations of the brains of different Vertebrates, in order 
to discover a means of defining the cerebellum, which displays so many 
structural differences in the different groups. He does not believe that 
the cerebellum can be regarded as a brain segment ; it is rather an inter- 
segmental structure originating as a parietal outgrowth of the neural 
tubs. The difficulties of defining the limits of this outgrowth are 
great, but the author finds that in Selachians there is a distinct circular 
groove, which surrounds the inner wall of the neural tube in the neigh- 
bourhood of the primitive furrow between mid- and hind-brain. This 
groove syems to be constant throughout the Vertebrate phylum, and it 
marks the boundary between mid-brain and cerebellum. The result of 
the research is therefore to define the limits of the development of 
the cerebellar substance during embryonic life ; in the higher Verte- 
brates the cerebellum undergoes many later changes, and comes into 
complex relations with the other regions of the brain. The author 
proposes the term Sulcus raeso-metence^Jialicus interims for the circular 
groove. 
* Tom. cit. , pp. 41-2. 
f Jen. Zeitschr. f. Naturwiss., xxxiii. (1899) pp. 191-262 (6 pis.). 
X Anat. Anzeig. (Erganzungsheft), xvi. (1899) pp. 102-15 (10 figs.). 
