ZOOLOGY. 351 



the atmosphere. The ozone (electrified oxygen) thus given out is the best 

 purifier of the atmosphere. 



19. Care must be had not to allow any linen to be washed which is soiled 

 with the excrements of a cholera patient. The process of maceration to 

 which soiled clothes are usually subjected is capable of developing and com- 

 municating the disease in its worst form. Jameson found the same truth in 

 1817, '18 and '19 in India, without tracing it to its source. 



20. There are no other sanitary regulations capable of preventing or arrest- 

 ing cholera in its progress, than those which have reference to cleaning and 

 purifying those places which serve to collect or convey human excrements. 



OX THE ANATO^IY OF THE TOBPEDO. 



Professor J. Wyman recently presented to the Boston Society of Natural 

 History the result of some observations on the torpedo, well known for its 

 electrical powers. His attention had been particularly directed to the termi- 

 nation of the nerves in the lamiuce which compose the efficient part of the 

 battery. The plates consist of an exceedingly thin membrane which appears 

 to be nearly homogeneous, its surface showing only traces of striations. On 

 this membrane are distributed ultimate nerve fibers and capillary vessels. 

 When the primitive nerve-tube reaches the plate it breaks up into numerous 

 fibers, and these in turn subdivide and reunite so as to form a regular net- 

 work over the whole surface. Professor TVyman estimated the whole number 

 of the plates at between 250,000 and.300,000. There were about 100 to the 

 inch in each electric prism, which is less than the number counted by Mr. 

 Hunter, viz., 150 to the inch. The number of prisms in each battery- was 

 about 1,200, each prism measuring from 1 to 2 inches in height. The inter- 

 val between the plates was filled with a fluid consisting of about 90 per cent, 

 of water, containing albumen and common salt in solution. On examining 

 the contents of the stomach, it was found that during the process of the diges- 

 tion of the bones, the calcareous matter was removed before the gelatinous 

 matter was dissolved, and Dr. TTyman had noticed the same result in the dis- 

 section of other fishes. This is the reverse of what occurs in dogs and hyenas, 

 where the gelatinous matter alone is removed, the calcareous matter not being- 

 dissolved. The stomach of the specimen had been acted upon by the gastric 

 fluid after death, and was perforated in its large curvature. Hydrochloric 

 acid was detected in its contents. 



Professor Rogers alluded to the analogy betweeen this animal battery and 

 the ordinary metallic battery. The nervous tissue might act both as generator 

 and conductor, generating in its minute ramifications, and conducting by its 

 larger branches. The disproportionate quantity of nervous tissue would not 

 be an objection to this, as batteries are constructed in which the copper-plate 

 bears but a small proportion in size to the zinc, not more than one-twelfth 

 perhaps, which yet exert a powerful effect, especially when a hot acid is em- 

 ployed. 



