On the fertilizing and cytolytic effect of soap

Abstract

It has been shown by experiments on the eggs of sea-urchins, starfish, and annelids that the artificial membrane formation is the act which causes the unfertilized egg to develop. The agencies which cause the artificial membrane formation, as a rule, injure the egg. For the eggs of the starfish and certain other annelids this injury is rather slight, and these eggs are able to develop into larvæ without any further treatment. In the egg of the Californian sea-urchin this secondary, injurious effect connected with the artificial membrane formation is more severe and demands a further treatment of the egg. This consists in preventing the eggs from developing for about from two to three hours after the membrane formation, by depriving them of oxygen or by preventing oxidations in the egg through the addition of a trace of potassium cyanide. During this time the egg is able to recuperate from the injurious effects of the membrane formation and is able to develop perfectly normally into a pluteus if transferred into normal sea-water. In my first experiments with this method, four years ago not more than ten per cent. of the eggs could be caused to develop in this way. I have recently found that by a slight improvement of the method all the eggs can be caused to develop into larvæ, The segmentation is as a rule as normal as if the eggs were fertilized by sperm. A second method of overcoming the injurious effect caused by the artificial membrane formation consists in putting the eggs for from 10 to 40 minutes into hypertonic sea-water. This method also causes all the eggs to develop.