EXTRACT LIII. 



ON THE PHENOMENON OF CILIARY MOVEMENT IN 

 THE CIRCULATION OF CEREBRO-SPINAL LYMPH, 

 AND OF AIR AND MATERIAL PARTICLES IN THE 

 LUNGS. 



WHETHER ciliary movement of the lining membranes of 

 the early, and of even the later circulatory passages of the 

 embryo, always occurs as a phenomenon of circulatory 

 assistance, it is difficult to say, but it is true that the 

 phenomenon occurs during or in its latest stages of 

 growth, and becomes more and more obvious as early 

 foetal life progresses. Thus, at that stage, when the 

 neurenteric canal becomes divided into neural and 

 enteric, and when the free and general circulation of 

 its enclosed lymph, which has hitherto been allowed to 

 occupy the whole lumen of the canal, gives place to a 

 very restricted circulation at the line of division, which 

 to some extent is compensated for by the opening up 

 of an anterior means of circulation and evacuation, by 

 which the narrowing lumen of the neural canal is 

 maintained in physiologically necessary patency and fluid 

 fulness, to meet the varying conditions and wants of 

 the evolving systemic nervature, cerebral and spinal, 

 there is noted a growth on the lining membrane of 

 the whole future cranio-spinal inter-spaces of a ciliary 

 prolongation of the surface cells, in order to aid in the 

 process of the, then comparatively passive, lymph circu- 

 lation. 



In the ventricles and central canal of the cord, as they 

 become evolved by the increase of the true nervine 



