197 



the araclinoid space of the skull. The same methods of in- 

 vestigation as those spoken of ahove showed that this space is a 

 true lymphatic sac, its internal surfaces heing covered Avith a 

 regular epithelium. The same conclusion has, as is well 

 known, been arrived at by other observers Avith regard to the 

 arachnoid itself, so that the continuity of the whole system is 

 established. The final proof is given by throwing an injec- 

 tion into the arachnoid, which fills first the canal round the 

 optic nerve and the space of Tenon, then the perichoroid 

 space, and passes at the same time into the lymphatic vessels 

 of the neck, showing the continuity of these cavities with 

 the lymphatic system in general. Beside the canal just 

 spoken of as surrounding the whole optic nerve, to which the 

 author gives the name of s?q)ra-vaginal s-pace, there is another 

 included between the two fasciae of this nerve, which he calls 

 suboaginal. This is continuous with the arachnoid, from 

 which it may be injected, and surroimds the whole optic 

 nerve almost to its entrance into the eyeball ; but here it 

 stops short, not communicating with the proper lymphatic 

 spaces of the eye. Its inner surfaces have the structure of a 

 lymphatic sac, as distinctly as the perichoroid and other 

 spaces. 



Schwalbe makes some remarks on the method of investiga- 

 tion by impregnation with nitrate of silver. There can be no 

 doubt that the markings produced on serous surfixces cor- 

 respond to cell outlines ; but he thinks they are caused rather 

 by a precipitation of silver upon the edges of the cells by some 

 albuminous substance adhering to them, than by a staining of 

 any actual cement uniting the cells together. The term endo- 

 tliclia seems preferable, since they are not really identical 

 with ordinary epithelial cells. 



Lung. — F. E. Schultze, in the third part of Strieker's 

 handbook, gives a full discussion of the vexed question of the 

 alveolar epithelium. According to his observations, made 

 principally after injecting nitrate of silver into the air 

 passages, the whole surface of the alveoli and bronchial ter- 

 minations is in the foetus covered with a continuous and 

 homogeneous epithelium. After respiration is established this 

 epithelium, though not ceasing to be continuous, becomes hete- 

 rogeneous, and some of the cells, which are originally granu- 

 lar, polygonal, and clearly defined, become pale, transparent, 

 and indistinct, thus producing the appearance of a partial 

 epithelial covering, which has been described by many 

 observers. 



MiGKATORY Cells in the Skin. — Biesiadecki, in an ex- 

 cellent description of the skin, published in Strieker's ' Hand- 



voL. X. — new seb. o 



