74 PHYSICAL CHEMISTRY IN BIOLOGY. 



motic cleavage of esters is also to be mentioned (LOEVENHART and 

 PIERCE, AMBERG AND LOEVENHART l ). 



Other actions of salts are also ascribed to ion-action. To these 

 belong the experiments of DRESSER^ according to which mercury salts, 

 which are relatively strongly dissociated, have a poisonous action upon 

 organic formations (yeast, frog heart), while potassium-mercury hypo- 

 sulphite was nearly non-toxic. As the last-mentioned salt contains 

 very few free H ions the poisonous action of the first salt is ascribed to 

 the ions. PAUL and KRONIG 3 have arrived at similar results by inves- 

 tigating the poisonous action of mercury salts upon spores. They found 

 that K 2 Cy 4 Hg, which hardly contains any Hg ions, is much less poison- 

 ous than an equivalent solution of HgCy 2 . The same conditions were 

 observed by MAILLARD 4 for copper salts. 



In this connection it is interesting to mention the interesting inves- 

 tigations of J. LOEB 5 on the artificial fertilization of eggs of lower sea 

 animals. LOEB found that it is possible to obtain larvse from the unfer- 

 tilized eggs of the sea-urchin, Arbacia, which never develop in normal 

 sea-water. For this purpose it was only necessary to keep the eggs 

 for two hours in sea-water whose osmotic pressure had been raised 40-50 per 

 cent and then placing the eggs again in normal sea-water. It is immate- 

 rial how the osmotic pressure is raised, whether by the addition of NaCl, 

 KC1, MgCl2, urea, or sugar. It is evident that the bodies used are those 

 which cause an effective osmotic pressure. LOEB ascribes their action 

 to their ability to attract water. The development of the egg does not 

 take place exactly like an egg fertilized with spermatozoa. LOEB obtained 

 much better results by using the eggs of another sea-urchin, Strongy- 

 locentrotus, which he allows to lie first for J-l minute in sea-water slightly 

 acidulated -with a low fatty acid, foi instance formic acid, and then replaced 

 in normal sea-water. By this means chemical processes are introduced, 

 which when the eggs remain in sea-water causes death in less than 24 

 hours, but if the eggs, 5-10 minutes after the membrane formation which 

 takes place in sea-water, are kept for 20-45 minutes in hypertonic sea- 

 water, and then ag^in placed in normal sea-water, the development of 

 active larvse is the result. The presence of oxygen is necessary for the 

 result of the experiment. LOEB has also obtained larvae from other 



1 Journ. of Biol. Chem., 2, 397, 1907; 4, 149, 1908. 



2 Arch. exp. Pathol. u. Pharm., 32, 456, 1893. 



3 Zeitschr. f. physik. Chem., 31, 411, 1896. 



4 Compt. rend. soc. biol., 50, 1210, 1898. 



5 Loeb, Vorlesungen iiber die Dynamik der Lebenserscheinungen, 1906, 243; Pfliiger's 

 Arch., 118, 572, 1907; Ueber den chemiscLen Charakter des Befruchtungsvorganges, 

 Leipzig, 1908. 



