ON THE FUXCTIONAL ACTIVITY OF NERVE CELLS. 515 



extremely intimate, the above discrepancies suggest au inquiry as to the 

 efficiency of the methods hitherto employed in the investigation. These 

 have consisted in using repeated electrical currents as the exciting or 

 polarising agencies, and noting the gal vanometric effects produced by their 

 summation. The authors were led by some preliminary experiments to 

 infer that the time relations of such multiple effects differ from those of 

 a single change. In order to obtain the necessary I'ecord of a single 

 change, a new projection electrometer was constructed and fitted up in 

 connection with a photographic recording arrangement, in a room set 

 apart for the purpose in the physiological laboratory at Oxford. 



The new capillary electrometer is of the improved form referred to by 

 one of us (G. J. B.).^ It is less fragile than the older instruments, and 

 gives better definition with high magnifying power. In sensitiveness 

 and rapidity of action it is superior to those which we have hitherto 

 used. Great difficulties were met with at first owing to the transmission 

 of vibrations through the concrete floor to the pillar, which, although 

 placed in a well sunk 7 feet below the ground, did not furnish a satis- 

 factory base for our very sensitive instrument. These difficulties were 

 finally got rid of by the adoption of a special form of support. Since it 

 was essential to eliminate all vibration errors, a considerable part of the 

 grant allotted to this branch of the research has been devoted to the 

 construction of the stand just referred to. 



The experiments are still in progress, but a large number of photo- 

 graphic records have been already made, particularly of polarisation effects 

 and after-effects. These have been obtained in the following polarisable 

 objects : (1) Schema on Hermann's model — i.e., platinum wire core in 

 saturated solution of zinc sulphate ; (2) sciatic iierve ; (3) sartorius 

 muscle. 



1. Schema. — The capillary records of the extrapolar polarisation 

 effects produced by a single polarising current give on analysis results 

 which show that the propagation rate is not the same as that obtained 

 from similar experiments carried out by the authors by the repeating 

 rheotome and galvanometric record. The differences between the two sets 

 of results seem to indicate that the rheotonic effects are confused by the 

 presence of a complexus of electrical states. 



2. Nerve. — The records with nerve exhibit several suggestive chai'ac- 

 teristics, but this part of the investigation is still in progress, and further 

 reference to it would at present be inadvisable. 



3. Muscle, — The sartorius muscle was utilised to determine the cha- 

 racters of the capillary records of the two classes of anodal after-effect, the 

 polarisation anodal positivity and the excitatory anodal negativity. These 

 records show, among other facts, that when the excitatory effect is pro- 

 duced it not only swamps the polarisation one, but increases in extent for 

 some little time after the cessation of the polarising current. The records 

 of the excitatory after-effect are further remarkable in showing no indica- 

 tions of oscillation ; it would therefore appear that this anodal excitatory 

 change is not a rapid series of states but a single prolonged change. It is 

 thus distinguished from other excitatory changes of similar duration, and 

 cannot be regarded as a response of the same order as that produced by 

 successive stimuli. 



' G. J. Lurch, 'The Electrometer in Theory and Practice,' The IlecUicia^, 1896. 



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