THB SWAMPS OF XHB MISSISSIPPI. 119 



the Organiste of Haiti, about which Jso much superstition and mystery 

 prevail ; but fever, arising from misfortune, completely defeated me in this 

 attempt. 



Mill of Boundie, near Banff, Dec. 29f A 1853. 



Olf THE EXPANSION AND CONTRACTION OF BRITISH LAND 



SHELLS. 



BY H. R. BOLTON, ESQ. 



My attention, for some time past, has been called to the occasional expan- 

 sion and contraction of our common hedgerow Snails during the period of 

 life, more particular'ly those of the larger species, Helix pomatia, H. aspersa, 

 H. arbustorum, &c., some of which I obtained and kept in my own garden, 

 and find that, after the animal has ariived at maturity, the size of the shell 

 frequently varies, according to the dryness or dampness of the atmosphere, 

 and plenty or scarcity of food. Of this I am fully convinced, from constant 

 observation and experiments. 



After two or thi'ee days of successive warm and congenial showers, placing 

 plenty of food within their reach, such as lettuce, I have measured a full 

 grown H. pomatia, and found the circumference round the largest whorl 

 measure four inches and nine tenths. I have then placed the same animal 

 for twenty days in a dry situation, exposed for an hour or two each day in 

 the sun, depriving it the whole period from food. After this, on again 

 measuring it, I have found its decrease in size to have been four and a half 

 tenths of an inch, measuring now but four inches and four and a half tenths. 

 On replacing it again in a moist situation, with food, after a few wet days it 

 has obtained its former dimensions. 



I have also tried the same experiment on H. aspersa, the specimen I 

 committed to that ordeal when in high condition. I found the circumference 

 to have been 3 8, the decrease being three tenths of an inch. This also, on 

 being returned into the damp and good keep, soon arrived at its primitive 

 size. In experimenting on many other species, I found a similar deci'ease 

 in proportion to their size. 



I have generally observed, that all our Land Shells decrease in size after 

 death, and the animal is taken out, to what they were while in a living and 

 vigorous state. 



Not having seen or read any obsei-vations in the works of our naturalists 

 on this expansion and contraction of Shells, induced me to trouble you with 

 these few remarks, as, perhaps, some of your readers will follow the matter 

 up further, by investigating how such alteration is effected on what appears 

 to be a hard and fixed substance. 



3, VaUetot Place, Stoke Devonport, April 2nd, 1855. 



