It has been shewn by Loeb that in Cerianthus or Tubularia, for instance, the cells in order to grow must be turgescent; and this turgescence is only possible so long as the salt water in which the cells lie does not overstep a certain limit of concentration. The limit, in the case of Tubularia, is passed when the salt amounts to about 5·4 per cent. Sea-water contains some 3·0 to 3·5 p.c. of salts; but it is when the salinity falls much below this normal, to about 2·2 p.c., that Tubularia exhibits its maximal turgescence, and maximal growth. A further dilution is said to act as a poison to the animal. Loeb has also shewn[157] that in certain eggs (e.g. those of the little fish _Fundulus_) an increasing concentration of the sea-water (leading to a diminishing “water-content” of the egg) retards the rate of segmentation and at length renders segmentation impossible; though nuclear division, by the way, goes on for some time longer. Among many other observations of the same kind, those of Bialaszewicz[158], on the early growth of the frog, are notable. He shews that the growth of the embryo while still _within the {126} vitelline membrane_ depends wholly on the absorption of water; that whether rate of growth be fast or slow (in accordance with temperature) the quantity of water absorbed is constant; and that successive changes of form correspond to definite quantities of water absorbed. The solid residue, as Davenport has also shewn, may actually and notably diminish, while the embryo organism is increasing rapidly in bulk and weight. On the other hand, in later stages and especially in the higher animals, the percentage of water tends to diminish. This has been shewn by Davenport in the frog, by Potts in the chick, and particularly by Fehling in the case of man[159]. Fehling’s results are epitomised as follows: Age in weeks 6 17 22 24 26 30 35 39 Percentage of water 97·5 91·8 92·0 89·9 86·4 83·7 82·9 74·2 And the following illustrate Davenport’s results for the frog: Age in weeks 1 2 5 7 9 14 41 84 Percentage of water 56·3 58·5 76·7 89·3 93·1 95·0 90·2 87·5