.- 



JRARt 



88 



T. H. MORGAN. 



The results show very clearly that the double solution has 

 acted more injuriously on the egg than the lithium chlorid alone. 

 The results appear, from a comparison with sugar solutions, not 

 to be entirely due to the increase in osmotic pressure, but to the 

 greater effect of the combined action of the sodium and the 

 lithium. 



EFFECTS OF LITHIUM CHLORID AND MAGNESIUM CHLORID 



ACTING TOGETHER. 



Eggs in the two- cell stage were put into a solution containing 

 LiCl 0.5 + MgCL 0.6 per cent. After two hours the eggs were 

 still in the two-cell stage. Two hours later the eggs were in the 

 i6-cell stage, some of them having divided with great irregu- 

 larity. Sections show a small segmentation cavity present. Two 

 hours later, Figs. 34 and 35, one or two further divisions have 

 taken place. As shown in these figures the egg is nearly solid, 

 and in other eggs there is no trace of the segmentation cavity. 

 Another division has taken place after two hours more, and 

 another division after another two hours. At this time the sec- 

 tions show the interior cell-walls running together to produce 

 polynuclear cells. Two hours later the egg is as before, or has 

 divided again, and after another four hours further division has 

 occurred, but in this and the following stages (after eight hours), 

 the cells especially the yolk cells are becoming polynuclear and 

 division is apparently near its end without having produced a 

 large number of cells. It is noticeable that the yolk cells have 

 been more affected than the smaller cells of the upper hemi- 

 sphere. The results are similar on the whole to those with 

 LiCl + NaCl, but less marked ; the younger stages being more 

 regular. The segmentation cavity appears to have been prac- 

 tically obliterated. 



THE CHEMICAL VERSUS THE OSMOTIC EFFECTS OF THE SALT 



SOLUTIONS. 



In order to determine, if possible, how far the action of the 

 salt solutions is due to chemical effects and how far to osmotic 

 effects, the following experiments were carried out with the eggs of 

 Rana sy/ratica. Eggs in the two-cell stage were put into solutions 



