ELECTKICITY — HEAT. 251 



highly gratified at the siglit of so brilliant and singular a 

 creature."* 



9. Electricity. — In the Edinb. New Philosophical Jour- 

 nal, viii. 204, you will find the following paragraph : — " Mr. 

 Calder mentioned to the Asiatic Society of Calcutta, a 

 molluscous animal which has the property of giving electric 

 shocks, like the torpedo and gymnotus ; but neither genus 

 nor species of the animal is noticed." 1 am not aware that 

 any further notice of it has been published ; but I have 

 somewhere read that a species of cuttle-fish had been ima- 

 gined to possess an electric or galvanic power, and to be 

 thereby assisted in subduing its prey ; as the sensations of 

 persons seized upon or touched by the arms of the Cephalo- 

 pod were stated to be more painful than any which mere 

 mechanical violence of equal force could produce. 



10. Heat. — The mollusca have likewise the property of 

 generating heat, though, like other cold-blood creatures, 

 their warmth is much under the control of, and varies with, 

 the atmospheric temperature. Mr. John Hunter found, when 

 the atmosphere was 54°, that four black slugs, put into a 

 small vessel, raised the thermometer to 55° and a quarter. -j- 

 The experiments of Spallanzani and Gaspard had the same 

 result; while those of Dr. Davy, made on a large snail that 

 abounds in the woods of Ceylon, indicated no change, even 

 after the snail had been confined for eight hours. J "Accord- 

 ing to Berger's experiments, the heat of Helix pomatia 

 varies exceedingly with that of the atmosphere. Its medium 

 warmth was 8"33° during eleven months, the minimum 2'22°, 

 and the maximum 18*33°. In summer it was mostly at 4*44° 

 at sunrise, and at 12*22° towards two o'clock in the after- 

 noon. The heat of bivalve mollusca is, according to Pfeifier, 

 nearly the same as the temperature of the water in which 

 they live. He found the water in which they were kept to 

 stand at 11*25°, whilst the bulb of the thermometer, placed 

 between the belly and the branchial lamellag, rose only to 

 11*56°. J. Davy says he never remarked any difference 

 between the heat of oysters and of the water in which they 

 were." § 



* Zdol. Illustr. i. 43-4. — Mr. Bennett has described some other remark- 

 able instances of phosphorescence by the Pyrosoma in his " Wanderings in 

 New South Wales ;" and in the Proc. of the Zool. Soc. of London. — Sec in 

 ])articular, vol. iii. 79, 80. + Anini. Econ. p. 117, exp. 31. 



X Edinb. Phil. Journ. xiv, 43. § Tiedcniann's Comp. Physiology, p. 245. 



