212 



Dr A. Durisj. A Contribution to 



[lS T ov. 20, 



" A Contribution to the Question of Blaze Currents." By Dr 

 Arnold Durig, of Yienna. Communicated by Augustus D. 

 Waller, M.D., B.B.S. Beceived November 20,— Bead 

 December 4, 1902. 



(From the Oxford Physiological Laboratory.) 

 (Translated from the German by Miss F. Buchanan, D.Sc.) 



The numerous experiments of Waller on this subject have raised 

 the question as to whether the phenomena of the so-called " blaze 

 currents " are to be regarded as a proof of the persistence of life. It 

 is the purpose of the present communication to give the results of a 

 few experiments which bear upon the subject. These relate princi- 

 pally to the response of the eyeball, but also to that of a few other 

 organs of the frog, to single induction shocks. As they are not yet 

 definitively concluded, I propose here to give only a short description 

 of them, and not to refer to their theoretical significance beyond 

 pointing out that the results obtained must be taken into account 

 before deciding whether or not the currents in question furnish an 

 unmistakable sign of vitality in tissues. 



As regards method, the great importance of determining the exact 

 moment after excitation, when the first trace of a current appears, 

 must be insisted upon. It is essential to know whether or not it is 

 after a latent period, and to know its direction, in order to ascertain 

 whether, in addition to the reaction of living tissue, polarisation effects 

 are also being observed. The capillary electrometer has advantages 

 over the more inert galvanometer for this purpose, since the velocity 

 with which the meniscus moves when it first begins to be acted upon 

 by a difference of potential, as determined from the photographic 

 record of the excursion, would enable one to recognise the existence 

 of a polarisation current when it is in the same direction as the " blaze 

 current." Such records have, however, still to be made. The dia- 

 gram shows the arrangement of the apparatus employed. 



By the commutator Ci in the primary circuit, the direction of the 

 exciting current could be reversed. By means of C 2 the current could 

 be sent to the primary coil either direct or after passing through a 

 Neef's hammer. The key, Ki, served to determine whether the 

 current should be made or broken, the spring-myograph, M, opening 

 accordingly, either the primary circuit itself, or a bridge short- 

 circuiting it. It was thus possible to excite the preparation in imme- 

 diate succession by ascending or descending, make or break, induction 

 shocks, and to excite it after faradisation by a single shock in either 

 direction. Another contact, for short-circuiting the galvanoscope, 

 was so arranged as to be broken by the myograph immediately after 



