230 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



bottom. It would bump hard against the side of the cage, as if that 

 obstacle were not seen, and then follow the wall upward to the surface 

 with its head curved dorsally. On the following day it swam about 

 as actively and responded as quickly to tactile stimuli as its com- 

 panions which had not been operated upon. When a stick or an oar 

 was suddenly placed in front of it, the effort to avoid the obstacle came 

 apparently too late to prevent collision. 



Squalus Nos. 2, 3, and 4 recovered more quickly from the shock of 

 the operation than No. 1 did. In No. 4 there was scarcely any appar- 

 ent shock. Compared with normal individuals, these three showed the 

 same slowness of response to optical stimuli as did No. 1. On the third 

 day all these individuals became sluggish and died on the fourth or fifth 

 day. Autopsies performed on all of them showed the tela more or less 

 torn and congested. The central nervous system was not otherwise in- 

 jured. There was every evidence that the fibre had been broken, but 

 the brain and anterior portion of the cord were preserved for micro- 

 scopical examination to determine this absolutely. Death was caused by 

 diffuse meningitis, both spinal and cerebral. In teased specimens of the 

 dura mater numerous bacteria, cocci, and bacilli were present. The 

 membranes were deeply injected and the wounds more or less ulcerated.^ 

 Had antiseptic and waterproof dressing been devised for these animals, 

 it seems probable that they would have recovered from the operation, 

 though it is true that sharks have shown almost no capacity to heal 

 wounds or regenerate skin. Liquid i-ubbei", collodion, and other dressings 

 were used, but were less satisfactory than vaseline. 



Squalus No. 5 gave evidence of severe shock after the operation, 

 probably because it was abnormal at the time, having been confined for 

 some months previously. It, however, showed the normal response to 

 optical stimuli, not the slow response observed in the previous cases. 

 In Squalus No. 6 the same operation was performed, but care was taken 

 not to injure Reissner's fibre. After recovery from shock, it responded 

 quite normally to optical stimuli. 



Of tlie three specimens of Mustelus operated on, two gave substan- 

 tially the same results as Squalus No. 1 ; the third, the same as Squalus 

 No. 5. Two sand sharks (Charcharias) were operated on, but the re- 

 sults were unsatisfactory. There was no recovery from shock, and no 

 characteristic reactions could be observed. 



The great difficulty in carrying on these experiments with water 



1 For assistance in performing these autopsies I am indebted to Dr. H. H. 

 Cashing, of Jefferson Medical College. 



