1425 
form the primitive homologon of Purkinje cells. The cells lie irregularly 
about the middle of the cerebellum under the molecular layer, which is 
largely formed by the fine neurones of the afferent systems. Regarding 
the connections of the cerebellum and of the nuclei lying in its 
proximity, little is known with certainty. 
According to SCHILLING, the poorly developed tractus cerebello- 
lobaris runs out of the cerebellum into the mid-brain. According to 
other investigators, however, this is more probably an ascending 
tract. Caudally from there, according to Crarx'), there is a tractus 
tegmento-cerebellaris (or better, a tractus cerebello-tegmentalis) which 
may be identical with the tract described by JonnsTon *) as “arcuate- 
fibres from the cerebellum”. Where, however, the cerebello-fugal tracts 
deseribed originate is nowhere exactly indicated, not even on which 
level the investigator lost sight of them. ScHirriNG, in his drawing 
of a sagittal section, gives a brachium conjunetivium, but without any 
particulars. 
In a series of frontal sections coloured with haematoxyline which 
I examined, | found two groups of fibres which I must mention in 
this connection. I have drawn one section of this series (Fig. 1). 
cellule eral anes 
Fig. 1. Petromyzon fluviatilis. 
1) Crary, The cerebellum of Petromyzon fluviatilis. Journ. of Anatomy and 
Physiology, Vol XI, 1906. 
2) Jonnston, The Brain of Petromyzon, Journ. of comp. Neurol. Vol. 12. 1902. 
