Artificial parthenogenesis and fertilization / by Jacques Loeb... Originally tr. from the German by W. O. Redman King... supplemented and revised by the author.

  • Loeb, Jacques, 1859-1924.
Date:
[1913]
Catalogue details

Licence: In copyright

Credit: Artificial parthenogenesis and fertilization / by Jacques Loeb... Originally tr. from the German by W. O. Redman King... supplemented and revised by the author. Source: Wellcome Collection.

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    is, however, 0.94 m, or isosmotic with sea-water. But this Solution acts just as hypertonically upon the sea-urchin egg as a 0.80 m NaCl solution, i.e., a solution whose osmotic pressure is about 50 per ceiit higher than that of a 0.94 m cane-sugar solution. It can be directly shown that a solution of cane sugar, which is theoretically isosmotic with sea-water, is actually hypertonic for the sea-urchin egg. For the eggs shrivel in such a solution; they even shrink in a 7/8 m cane-sugar solution; in a 6/8 m solution they retain their volume and in a 5/8 m solu- tion they increase in size. Eight years ago I also observed that medusae {Polyorchis) shrink considerably in a pure cane-sugar solution that is theoretically isosmotic with sea-water. It can be indirectly shown that a 3/4 m cane-sugar solution is about the concentration that is isotonic for the sea-urchin egg, by placing sea-urchin eggs that have been fertilized with sperm in pure cane-sugar Solutions of different concentrations immediately after fertilization. Experiments of this description showed that in a 6/8 m cane-sugar solution the first cell division occurs in all the eggs of purpuratus, and indeed at almost the same time as in normal sea-water; while in 5/8 and 7/8 m Solutions its onset is delayed and occurs in only a few eggs. In cane-sugar Solutions below 5/8 m and above 7/8 m as a rule not a single egg divided. In 6/8 m cane-sugar solution, again, the cleavage did not go beyond the four- or eight-cell stage, which is in accordance with the experience in muscle. But if the eggs are replaced in sea-water they develop normally. This behavior of the egg in a cane-sugar solution corresponds to the behavior of a medusa in the same solution: for in the latter, also, as well as in the heart, the spontaneous contractions cease in a pure cane-sugar solution.^ These observations have a bearing upon a controversy between Belage and the writer. Belage used in his experiments on artificial parthenogenesis cane-sugar solu- * Loeb, Am. Jour. Physiol., III, 384, 1900.