GERMINATION OF SEEDS 41 



content takes place upon fertilization. When two drops of a 

 1/100 grammolecular solution of neutral red are added to 50 c.c. 

 of sea-water, the sea-water immediately assumes a yellow color, 

 owing to its alkaline reaction. 



If now unfertilized and freshly fertilized eggs of the sea-urchin 

 Strongylocentrotus purpuratus are placed at the same time in this solu- 

 tion, both kinds of eggs quickly take on a red color. But if, after 20 

 to 40 minutes, they are brought back into normal colorless sea-water, 

 the unfertilized eggs gradually lose their color, while the fertilized 

 eggs become a still deeper red. One receives the impression that, 

 while the unfertilized eggs give up again the coloring matter to the 

 surrounding sea-water, the fertilized eggs continue to take it up. 

 After about an hour, therefore, two kinds of eggs are to be found in 

 the bowl of sea-water, some colorless, or very slightly colored, and others 

 colored a deep red; the latter are, without exception, eggs which possess 

 a membrane and, later on, segment toeing therefore fertilized eggs, 

 while the colorless eggs possess no membrane and are unfertilized. 

 Neutral red is an alkaline coloring matter, and therefore combines 

 in the egg with an acid. This retention of neutral red indicates that it 

 is held in closer combination in the fertilized than in the unfertilized 

 egg, where it can be quickly lost. 1 



The yolk of the egg contains a relatively large amount of fat 

 and lipoids. The eggs of most invertebrates are small, not very 

 far from the limit of vision of the unaided eye. Nevertheless 

 they contain reserve materials in relatively large quantities, 

 and among these reserve substances are found fats or lipoids. 

 Now it is quite possible, if not probable, that the commence- 

 ment of development in plant embryos possesses certain points 

 in common with that in the eggs of animals, viz., in regard to 

 the role of the decomposition of fats or lipoids. But it must 

 also be borne in mind that the fats or lipoids require a some- 

 what different treatment, according as they are the more solid 

 or liquid. In oil-containing plant seeds we have to deal mostly 

 with liquid oils; in animals the solid palmitin and stearin fats 



1 Loeb, " Weitere Beobachtungen ueber den Einfluss der Befruchtung und der 

 Zahl der Zellkerne auf die Saurebildung im Ei," Biochem. Zeitschr., II, 34, 1906. 



