THE STOKY OF NINETEENTH-CENTURY SCIENCE 



workers had introduced. Now for the first time it be- 

 came possible to trace the cellular prolongations definite- 

 ly to their termini, for the finer fibrils had not been 

 rendered visible by any previous method of treatment. 

 Golgi himself proved that the set of fibrils known as 

 protoplasmic prolongations terminate by free extremi- 

 ties, and have no direct connection with any cell save 

 the one from which they spring. He showed also that 

 the axis cylinders give off multitudes of lateral branches 

 not hitherto suspected. But here he paused, missing 

 the real import of the discovery of which he was hard 

 on the track. It remained for the Spanish histologist, 

 Dr. S. Ramon y Cajal, to follow up the investigation by 

 means of an improved application of Golgi's method of 

 staining, and to demonstrate that the axis cylinders, to- 

 gether with all their collateral branches, though some- 

 times extending to a great distance, yet finally termi- 

 nate, like the other cell prolongations, in arborescent 

 fibrils having free extremities. In a word, it was shown 

 that each central nerve cell, with its fibrillar offshoots, 

 is an isolated entity. Instead of being in physical con- 

 nection with a multitude of other nerve cells, it has no 

 direct physical connection with any other nerve cell 

 whatever. 



When Dr. Cajal announced his discovery, in 1889, his 

 revolutionary claims not unnaturally amazed the mass 

 of histologists. There were some few of them, however, 

 who were not quite unprepared for the revelation ; in 

 particular His, who had half suspected the independence 

 of the cells, because they seemed to develop from disso- 

 ciated centres ; and Forel, who based a similar suspicion 

 on the fact that he had never been able actually to 

 trace a fibre from one cell to another. These observers 



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