j , Introduction 



primeval instincts remain. And where the waters are 



clean, and shores unspoiled, thither we still go for rest, 



and refreshment. Where fishes leap and sweet water 



lilies glisten, where bull frogs boom and swarms of 



May-flies lmwr, there we find a life so different from 



| of OUT usual surroundings that its contemplation 



is full of interest. The school boy lies on the brink of a 



pool, watching the caddisworms haul their lumbering 



bout on the bottom, and the planctologist plies 



his nets, recording each season the wax and wane of 



generations of aquatic organisms, and both are satisfied 



irvers. 



The study of water life, which is today the special 



vinee of the science of limnology*, had its be^nning 



in the remote unclironicTe^jast- LimnologyTs" a ^ 



m< m [ern name ; 1 >ut many limnological phenomena were 



km >wn of old. The congregating of fishes upon their 



spawning beds, the emergence of swarms of May-flies 



from the rivers, the cloudlike flight of midges over the 



marshes, and even the "water bloom" spreading as a 



filmy mantle of green over the still surface of the lake — ■ 



such things could not escape the notice of the most 



ual observer. Two of the plaguesofEgypt were 



limnological phenomena; the plague "of frogs, and the 



plague of the rivers that were turned to blood. 



Such phenomena have always excited great wonder- 

 ment. And, being little understood, they have given 

 to most remarkable superstitions.! Little real 



*Limn<>s = shore, waterside, and logos = a treatise: hydrobiology. 



fThe f< 'Ik lore of all raees abounds in strange interpretations of the simplest 



limnological phenomena; bloody water, magic shrouds (stranded "blanket- 



pirits dancing in waterfalls, the "willo' the wisp" (spontaneous com- 



rsh gas), etc. Dr. Thistleton Dyer has summarized the folk lore 



last mentioned in Pop.Sci.AIontlily 19:67, 1881. InKeightly's 



Fairy Mythology, p. 401 will be found a reference to the water and wood maids 



rail .ire of a beautiful form with long green hair: They 



swing and balance themselves on the branches of trees, bathe in lakes and 



v on the surface of the water, and wring their locks on the green 



I at the water's edge." On fairies and carp rings see Theodore Gill in 



.Smithsonian Miscellaneous Collections 48:203, 1905. 



