XIII 1 . 



1. Introduction. 



DURING the past summer (1884) and this winter and spring- 

 (1884-5), through the kind co-operation of the Director of the 

 Berlin Aquarium, Dr. Otto Hermes, I have again had at my 

 disposal several living torpedos (T. marmorata) from Trieste. 

 Those in the summer were four females, I, II, III, IV, and 

 their respective lengths were 29-5, 35, 31-5, 31-5 cm. Torpedo I 

 arrived on June 9th, in a very sickly condition. As I worked with 

 it during the day its breathing was still regular, but it closed its 

 spiracles only partially, and it was evidently in a sort of opisthotonus, 

 so that its back was very concave in a sagittal direction. The 

 torpedos II, III, IV arrived on June 23rd, and were killed on 

 July 9th, July i6th, and August I3th respectively, after remaining- 

 for about 2, 3, 7 weeks in the tanks of the Berlin Aquarium. 

 The winter supply which was brought on October 22nd consisted 

 of three females, V, VI, VII, and their lengths were 28-5, 26-5, 

 28 cm. respectively ; they were killed on the 2ist and 3oth De- 

 cember, 1884, and on the 6th May, 1885, after a period of about 

 8, 9, 28 weeks. An accident befell a first consignment in spring 

 this year, but on May 8th a female (VIII), 34 cm. long, arrived 

 in good condition, and was experimented with on June 3rd. 



In the summer of 1883 I had also allowed three and five weeks 

 to elapse after the arrival of fish before killing" them, and in the 

 winter of 1883-84 a period of ten and fifteen weeks. The reason 

 of these delays is, that in order to make full use of a torpedo it is 

 necessary to devote two whole consecutive days to the work 

 without interruption, and my occupations only permitted this at 

 wide intervals of time. I mention this because the functional 

 activity of the fish naturally suffers very much from a prolonged 



1 See No. XII of this book. 



