shower will serve to trigger egg laying. 

 The snails crawl down the tree trunk, 

 dig a small hole in the leaf mold at the 

 tree's base, lay and then cover 15 to 50 

 pea-sized eggs that remain in the soil 

 until spring. The adults then ascend 

 the tree and seal themselves with an in- 

 ternally secreted cement to a limb or 

 under loose bark, there to remain dor- 

 mant until the rains return. This cement 

 is very strong, and if the shell is pulled 

 by a collector the bark or shell may 

 break before the glue loosens. When wet 

 weather returns, the snails dissolve their 

 seals and resume activities. 



The eggs hatch in the spring and the 

 young immediately crawl up the nearby 

 tree and begin feeding. Many young die 

 during droughts or are eaten by birds. 

 Those that survive attain adulthood in 

 four years and may live as long as nine. 

 Occasionally raccoons, rats, or opossums 

 eat adult snails, and some are taken by 

 collectors, but their greatest enemy is the 

 encroachment of housing and industrial 

 developments. 



The snails seldom move out of their 

 trees, can remain sealed to a limb for 

 nine or ten months, and can be sub- 

 merged in water for 20 hours without 

 harm. They have been observed to de- 

 scend trees en masse before the start of a 

 severe hurricane, with a less dramatic 

 descent preceding a milder storm. How 

 they sense the impending storm is un- 

 known. Occasionally, some specimen 

 sealed to a tree limb will be carried 

 great distances by high winds. If the 

 broken limb lands in a hammock and 

 the snail is not destroyed, a new colony 

 may possibly be started. 



In this possibility lies the key to the 

 scientist's interest. 



Untold millennia ago, such a tree limb 

 must have blown or drifted across the 

 water from Cuba to southern Florida. 

 Beached on the edge of a hammock, the 

 first Florida Liguus reproduced. At rare 

 intervals, other such accidental intro- 

 ductions spread Liguus across southern 

 Florida. Genetic mutations produced 

 new color variations in isolated ham- 

 mocks. Sometimes these colonies were 

 wiped out by fire. Occasionally two 

 forms reached the same hammock and 

 hybridized. With small original popula- 

 tions and only occasional interchange of 

 individuals between colonies, the oppor- 



tunity for new color variations to be pre- 

 served was great. Thus the multitude of 

 color forms originated and persisted. 

 Here is almost a classic type of differenti- 

 ation in minor characters among popu- 

 lations of one species. 



Nature has produced a vast pool of 

 pure populations that vary in minor 

 ways. Collections such as that made by 

 the de Boes give us a census of where 

 and when certain color forms exist. From 



this pool of information, experimental bi- 

 ologists can select different strains (color 

 forms) for experimental breeding. By 

 collecting young individuals from known 

 areas, crossing different varieties, and 

 comparing the progeny with the original 

 patterns, we can eventually hope to learn 

 how color pattern is genetically con- 

 trolled, thus adding to man's knowl- 

 edge of the mechanics and course of 

 evolution. 



Above: A shuffleboard pole and a "plumber's helper" assist Erwin Winte's "ligging" operation. 



Upper Left (title background): Polymita snail shells from Cuba's Sierra Maestra — like Liguus shells — are 

 among the most varied and brilliant known. 



Page 9 



