298 'Journal of Comparative Neurology and Psychology. 



on ganoid fishes, came to the conclusion that the columnar cells 

 of the membraneous portions of the brain must be of use in the 

 elaboration of the coeliolymph. He was led to this opinion by 

 the many evidences of secretion shown by the cells. Findlay 

 ('99), Galeotti ('97) and Studnicka ('go) all believed the plex- 

 uses secretory in function, and based their conclusions on the pres- 

 ence of secretory globules which will be discussed later. Cavaz- 

 ZANi ('93) advanced negative evidence, by showing that lympho- 

 gogues did not aflPect the flow of the cerebro-spinal fluid. He 

 therefore concluded that it was a secretory product of the epithelial 

 cells. 



To secure cerebro-spinal fluid, Cavazzani ('99) made use of a 

 cerebro-spinal fistula between the first cervical vertebra and the 

 occipital bone. Cappelleti ('01) used this fistula to study the 

 effect of certain drugs on the flow of the fluid. He found that 

 ethyl-ether and pilocarpin increase the flow, while atropin and 

 hyoscyamin retard the flow, sometimes even to the point of sus- 

 pending it. Of course these substances all have a vasomotor 

 action, but pilocarpin and atropin are supposed to aff^ect secre- 

 tory cells directly. Pettit and Girard ('o2-'o3) went a step far- 

 ther by administering drugs, such as pilocarpin, muscarin and 

 ether to animals, and then removing the plexuses to find whether 

 there was any evidence of secretion. Their results have amounted 

 almost to a demonstration of the origin of the cerebro-spinal fluid. 



The writer has made experiments along the same line as Cap- 

 pelleti and Pettit and Girard. No claim is made for origin- 

 ality, but it is hoped that a brief description of the results may be 

 of interest both as corroborative testimony and also because some 

 of the forms used had not been studied by the investigators just 

 mentioned. 



The canula described by Cavazzani for his cerebro-spinal 

 fistula is a rather complicated instrument. In practice it was 

 found that with care a simple glass canula with a short rubber 

 tube was satisfactory, at least for demonstrating the action of drugs. 

 The musculature is cleaned away and the dura mater over the 

 space between the atlas and the occipital bone laid bare. A small 

 puncture is made and the canula inserted. The elasticity of the 

 dura is enough to press the tissue against the tube, and thus avoid 

 loss of fluid or entrance of blood. In etherized dogs, the insertion 

 of the canula is followed by a rush of fluid. This is due to a secre- 



