(85") 



which we ave waiting for the cock to be free again, is used to 

 remove that wiiicli is deposited at the pkxce intended for tlie liquid 

 hydrogen. Thus it is not difïicult to prepare from the commercial 

 hydrogen large quantities of hydrogen with less than 1 pro mille of 

 admixture. 



Anatomy. — "On the development of the Cerebellum in Man''. 

 (Second Part). By Prof. L. Bolk. 



In the first part of this communication the development of the 

 Cerebellum is described until the stage in which the sulci appear 

 typical for the mammalian cerebellum. In this stage it is divided 

 by the sulcus primarius into an anterior and posterior lobe. The 

 first of these lobes is separated by three grooves into four lobules, 

 corresponding with the lobuli 1, 2, 3 and 4 of the mammalian 

 cerebellum. The posterior lobe is also separated by three grooves 

 (sulcus praepyramidalis, fissura secunda and sulcus uvulo-nodularis) 

 in four lobules, corresponding with the lobuli A (nodulus), B (uvula), 

 Cj, (pyramis) and C^ (declive -|- folium vei'mis -{- tuber vermis\ which, 

 with a few exceptions, are to be found in the other mammals. In 

 these exceptions the sulcus praepyramidalis, w^hich separates the lobuli 

 C, and C2, is missing, as in Erinaceus (Arnback Christie Linde), 

 Notoryctes (Elliot Smith), Vesperugo (Charnock Bradley), Chryso- 

 cldoris (Leche). In this case the posterior lobe is only built up of three 

 lobules. The missing of the sulcus praepyramidalis in these cerebella 

 of extremely simple construction gives rise to the supposition that 

 this fissure is phylogenetically the youngest of the primary sulci of 

 the cerebellum. This supposition is corroborated b}^ the fact that in 

 man the sulcus praepyramidalis is ontogenetically the last that appears. 



After the development of these pi'imary sulci, grooves appear 

 characteristic for the cerebellum of the primates, and whose homologa 

 are w^anting in other classes of mammals. 



In embryos of a length from 16 to 22 c.M. arises a groove on 

 the posterior surface of each of the hemispheres, the lateral part of 

 which is directed to the obtuse angle of the lateral border of the 

 cerebellum (Fig. 11 x)* The mesial ends of these grooves approaching 

 each other, penetrate into the narrow lobule which is bordered hy 

 the sulcus primarius (1) and by the sulcus praepyramidalis (4) ; after- 

 wards these grooves unite and divide the lobule in an up[)er and 

 lower half. This differentiation however not always proceeds sym- 

 metrically, so that it may happen, that these grooves do not meet, 



