Variation in animals and plants . s of dilution and concentration, seven tonine individuals being measured at each results are reproduced in the figure given the Specific Gravity of the water is representedalong the abscissa, and the amount of regeneration bythe height of the ordinates. We see that the maximumrate of regeneration took place in water of Sp. , or in very considerably diluted sea-water (the of this being about ). At this dilution the re- * Quart. Journ. Conch., i. p. 339. f Biological Lectures delivered at Woods Holl, 1893, p. 46. AN
Variation in animals and plants . s of dilution and concentration, seven tonine individuals being measured at each results are reproduced in the figure given the Specific Gravity of the water is representedalong the abscissa, and the amount of regeneration bythe height of the ordinates. We see that the maximumrate of regeneration took place in water of Sp. , or in very considerably diluted sea-water (the of this being about ). At this dilution the re- * Quart. Journ. Conch., i. p. 339. f Biological Lectures delivered at Woods Holl, 1893, p. 46. AND OF SALINITY. 279 generation was more than twice as fast as in normalwater, but with further dilution it rajpidly diminished,and ceased altogether in water of Sp. Gr. Somewhat similar results to these were obtained bythe author for sea-urchin plutei. As we saw in thelast chapter, the actual size of an organism is probablyaffected by environment in a similar manner to thegrowth rate, and the author found that these plutei,. Dilute Sea Water Concentrated Sea Water Specific GravityFIG. 24. — Effect of salinity on growth of Tubularia. allowed to develop in sea-water of various concentra-tions, attained a greater size than the normal when keptin moderately diluted water, and probably a slightlysmaller size when kept in concentrated water. Theresults obtained are indicated in the subjoined figure,where the abscissae represent the salinity of thewater, and the ordinates the average percent-age variation in the size of the larvae after eightdays growth, as compared with that of larvae grownin normal sea-water. The salinity of normal waterwas taken as 1000, and the less saline waters were * Phil. Trans. 1895, B. p. 586. 280 THE EFFECT OF MOISTURE. obtained by diluting respectively 950, 900 c. c., etc.,of water to a litre; the more saline by concentrat-ing 1050, 1100 c. c., etc., to a litre. The maximumeffect on size was produced by a solution containing50 c. c. of fresh w
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