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FISHERY BXJLLETIN OF THE FISH AND WILDLIFE SERVICE 



Shipley's account of the persistence of the 

 blastopore and his statement that invagination 

 took place at 130 hours suggest that embryos of 

 the lamprey developed at a temperature of about 

 55° F. It appears then that neither he nor 

 McClure conducted their experiments within the 

 range at which normal development could bo 

 expected. If the relation of temperature to 

 development in Lampetra is similar to that in 

 Petromyzon, Damas' experiments at 18° C. (64.4° 

 F.) should have been at nearly the optimum 

 temperature, but those conducted 12° C. (53.6° F.) 

 were well below the optimum. Thus, certain of 

 the abnormalities (most of them duplicated in the 

 present study, particidarly at the higher and lower 

 temperatures) that he interpreted as the effect of 

 light intensity may actually have been caused by 

 temperature. 



Although the findings of the present experiments 

 offer the strongest evidence that unsuitable tem- 

 peratures may account for the failure of certain 

 apparently suitable streams to produce larval sea 

 lampreys, a too close application of the results to 

 problems in nature is not advisable. The sea 

 lamprey eggs were reared at constant temperatures 

 in this study, whereas the temperatures in natural 

 streams are subject to diurnal fluctuations, to sub- 

 stantial short-term increases and decreases along 

 with changes of weather, and finally to a longer 

 term, seasonal, upward trend as development pro- 

 ceeds. These fluctuations may have a profound 

 effect on the tolerance of the developing egg. 

 Temperature surely is an important, sometimes a 

 critical, factor in the production of viable larvae 

 in nature, but a good understanding of its opera- 

 tion would require controlled investigations in 

 which eggs develop under fluctuating temperatures 

 which are made to vary much as they do in natural 

 streams. 



LITERATURE CITED 



AppLEGATE, Vernon C. 



1950. Natural history of the sea lamprey, Pelromyzon 

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 Service, Spec. Sci. Rept.: Fisheries, No. 55, 237 pp. 



Applegate, Vernon C, and James W. Mofpett. 



1955. The sea lamprey. Sci. Amer., vol. 192, No. 4, 

 pp. 36-41. 

 Applegate, Vernon C, and Bernard R. Smith. 



1951. Sea lamprey spawning runs in the Great Lalves, 

 1950. U.S. Fish and Wildlife Service, Spec. Sci. 

 Rept.: Fisheries, No. 61, 49 pp. 



Applegate, Vernon C, Bernard R. Smith, and Alber- 

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1952. Sea lamprey spawning run in Great Lakes, 

 1951. U.S. Fish and Wildlife Service, Spec. Sci. 

 Rept.: Fisheries: No. 68, 37 pp. 

 Augustinsson, K. B., R. Fange, A. Johnels, and E. 



OSTLUND. 



1956. Histological, physiological and biochemical 

 studies on the heart of two cyclostomes, hagfish 

 (Myxine) and lamprey (Lampetra). Jour. Physiol., 

 vol. 131, pp. 257-276, 

 Greaser, Charles W. 



1932. The lamprey Petromyzon marinus in Michigan. 

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 Gresticelli, Frederick. 



1956. The nature of the lamprey visual pigment. 

 Jour. General Physiol., vol. 39, pp. 423-435. 

 Damas, H. 



1944. Recherches sur le developpment de Lampetra 

 fluviatilis. Arch, de Biol., vol. 55, pp. 1-284. 



1948. L'influence de la lumiere sur la segmentation 

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 7-10, pp. 286-292. 



1949. Nouvelles observations sur l'influence de la 

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Daniel, J. 



1931. Features in ammocoete development. Univ. 

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 Gage, Simon H. 



1928. The lampreys of New York State — life history 

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GUSTAFSON, TrYGVE. 



1950. Morphogenetic action of Li ion and chemical 

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Hatta, S. 



1914. On the mesodermic origin and the fate of the 

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HuBBS, Carl L. 



1943. Terminology of early stages of fishes. Copeia 

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1937. The spread of the sea lamprey through the 

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1937. A revision of the lamprey genus Ichthyomyzon. 

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 109 pp. 



