ARTIFICIAL PRODUCTION OF NORMAL LARV.E 579 



the concentration is a little higher, the dissolution of the 

 nuclear membrane occurs, but the protoplasm on account of 

 its rigor is unable to scatter the chromosomes and to seg- 

 ment. If such eggs be put back into normal sea-water, the 

 protoplasm gradually loses its condition of rigor. The 

 motions that lead to the scattering of chromosomes return 

 sooner than the ability to segment. In such cases the pro- 

 cess probably occurs in the form in which Morgan observed 

 it. There may be intermediate stages and variations. 



I mention these experiments mainly for the reason that 

 they led Morgan to a very important step, namely, to try the 

 effect of an increase in the concentration of sea-water upon 

 unfertilized eggs. He found that eggs that were put into 

 sea-water whose concentration had been raised by the addi- 

 tion of 1^ per cent. NaCl or 3^ per cent. MgCl 2 began to 

 segment into two or more cells when put back into normal sea- 

 water. This segmentation went in some cases about as far as 

 the sixty-four-cell stage, but then the development stopped. 1 



Meade made the observation that the unfertilized eggs of 

 ChaBtopterus could be caused to throw out the polar bodies 

 by the addition of a small amount of KC1 to sea-water. 

 The addition of NaCl had no such effect. 2 Last year Dr. 

 Mathews made an experiment with rennet ferment which he 

 did not publish. In a previous paper on the origin of 

 fibrinogen he had expressed the idea that the origin of 

 the astrospheres in a cell was due to a process of coagu- 

 lation. He tried the effect of rennet ferment upon unfer- 

 tilized eggs of the sea-urchin to see whether he could in this 

 way cause the egg to develop. The eggs were put into a 

 solution of rennet tablet and when taken out began to seg- 

 ment, but the development did not go beyond the division 

 into a comparatively small number of cells. The phenomenon 



1 T. H. MORGAN, Archiv filr Entwickelungsmechanik, Vol. VIII (1899), p. 448. 



2 MEAD, Lectures delivered at Woods Hole, 1898 (Boston : Ginn & Co.). 



