146 Notes and Memoranda. 



made, but it is allowed to be inferred that the frog was discovered 

 in the coal when the latter was excavated. 



The accounts of living frogs being found enclosed in trees or 

 blocks of recent formation are never found to bear the test of scien- 

 tific scrutiny ; the occurrence of a living animal of the most recent 

 creation in a formation of such a degree of antiquity as the coal 

 measures, is perfectly impossible. The animal should be turned 

 over to some travelling show-van, containing mermaids and sea- 

 serpents, its being shown in the International Exhibition is calculated 

 to render the management of the scientific department the object of 

 ridicule to all intelligent foreigners — in the name of the scientific 

 men of this country we strongly protest against the continued 

 exhibition of this ridiculous absurdity. 



NOTES AND MEMORANDA. 



Temperature oe Snails. — M. J. B. Schnetzler lias been experimenting on 

 the temperature of the terrestrial mollusks, and has arrived at some interesting 

 results, which are recorded in the Bulletin Scientifique. He began with the 

 Helix pomatia, the large pale fawn-coloured snail, not uncommon in our lanes 

 and woods, and which is considered fine eating by epicures abroad. In April, 

 1861, when the air temperature was 12M Cent., a snail of this kind was a little 

 warmer, 12°. 5. In June, when the air was 23°.7, the thermometer, when covered 

 with the snail's foot rose to 24°. 7. A few days later, when the thermometer stood 

 at 18°. 7, it rose on being introduced into the snail shell, and brought as near the 

 respiratory cavity as possible, to 20°. Irritating the muscles of the animal gave a 

 further rise of .75°. In July a lively Helix pomatia, by mere contact of its foot, 

 raised the thermometer 2J- centigrade degrees.* Half an hour later, the air rose 

 one degree, but the snail remained the same. In September, after some snails had 

 closed their shells for a month, a shower of rain came, and although they were 

 kept in a room, they woke up, but their temperature did not exceed that of the 

 surrounding air. In January he placed two snails in the open air, having removed 

 their operculum. During the night the temperature fell to — 2 D Cent., but they 

 were not injured ; on a subsequent night, at — 8°, they froze and died. Slugs 

 have a lower temperature than snails. M. Schnetzler proposes to call these crea- 

 tures " animals of variable temperature," in contradistinction to mammals and 

 birds whose temperature is usually more equal, if we except the changes which 

 hybernating mammalia undergo. Mollusks may become colder than the air, by 

 evaporation from their skin, and Dutrochet found that frogs became noticeably 

 warmer in air saturated with aqueous vapour, and, consequently, suspending their 

 evaporation. 



Cleaning Engravings. — Dr. Hayes, of Massachussetts, in the Scientific Ame- 

 rican, recommends old dirty engravings first to have any pencil marks removed 

 with india-rubber or bread crumbs, then to have every spot saturated with solution 

 of oxalic acid in the proportion of one ounce to a quarter of a pint of warm water. 

 A few hours afterwards the engravings may be placed in a tub or foot-bath, being 

 allowed to rest upon a piece of open cotton stuff, such as ladies used to employ for 

 stiff petticoats before the return of hoops. This material, of suitable dimensions, 

 should have two rods or sticks sewn to opposite edges. These sticks will hang 

 over the sides of the vessel, and permit the prints to be withdrawn or moved with- 

 out any risk of injury, and they should remain in soak with warm or cold water 

 for twelve or twenty-four hours. When the prints no longer discolour the water 

 on being agitated, the fluid should be withdrawn, and enough clean water added to 

 cover them. Half a pound of chloride of lime should be made into a paste with 



* A degree of Fahrenheit is equal to five-ninths of a degree of the Centigrade scale. 



