130 Diffusion and Osmotio Peessdee 



tial feature in this increase in the osmotic pressure of the 

 surrounding solution is a loss of water on the part of the 



egg." 



Furthermore, the same author showed that a similar arti- 

 ficial parthenogenesis may be brought about in the case of 

 Chsetopterus, a marine annelid. Here another method of 

 treatment would also bring it about, namely, a slight increase 

 in the amount of potassium in the medium without any 

 increase in its concentration. This is termed by Loeb 

 chemical fertilization in contrast vjiWi physical fertilization, 

 the form described above. Chemical fertilization by potas- 

 sium is, so far, impossible in the eggs of Echinoderms. Very 

 recently Loeb and Neilson' have shown that chemical ferti- 

 lization by means of hydrogen ions is possible with eggs of 

 Asterias, and the same sort of fertilization, but with cal- 

 ciumions, was brought about by Loeb and Fischer' in the 

 case of eggs of the marine annelid, Amphitrite. These 

 phenomena are interesting here mainly as they show that a 

 chemical influence can bring about the same effect as extrac- 

 tion of water. 



That plants grow less rapidly in concentrated solutions 

 than in more dilute ones was first stated by Jarius,^ who 

 worked on the germination of seeds. With growing plants, 

 Stange' showed that Pisum, Phaseolus, Lupinus, etc., 

 increase in thickness more rapidly in concentrated solutions, 

 while more rapid growth in length occurs in dilute ones. 

 He suggests that the effect of the solution may be different 

 upon the meristematic cells of the growing point and upon 



1 J, Loeb, M. Fischee, and H. Nbilson, " Weitere Versuche ttber kflnstliche 

 Parthenogenese," Vorlaufige Mittheilung, Pflllgera Arch. f. d. ges. Physiol., Vol. 

 LXXXVII (1901), pp. 594-6. 



2 M. Jabics, "Ueber d. Einwirkung von SalzlOsungen auf d. Keimungsprocess d. 

 Samen einiger einheimisoher Culturgewaohse," LandwirUch. Versuchs-Stat., Vol. 

 XXXII (1886), pp. 149-78. 



3 B. Stangb, " Beziehungen zwisctxen Substratconoentration, Turgor und Wachs- 

 turn bei einigen phanerogamen Pflanzen," Bot. Zeitg., Vol. L (1892), p. 253. 



