November 8, 1912] 



SCIENCE 



639 



m/8 NaCl solution; that tlie muscle also be- 

 gins to swell after some time in a neutral 

 hypertonic l^aCl solution, while it shrinks in 

 a sufficiently hypertonic NaCl solution if the 

 latter is rendered acid. He ventured the sug- 

 gestion that this might be a protein reaction.* 

 This suggestion has since been amply corrobo- 

 rated ■ by the work of Hardy, Procter and 

 Pauli. It was, moreover, found that this an- 

 tagonism between acid and salt is much 

 stronger for the system H„SO^ — Na^SO^ than 

 for the system HCl — ISTaCU 



These data were utilized to find out whether 

 the specific impermeability of the membrane 

 of the egg of Fundulus is due to lipoids or to 

 proteins. It was found that when eggs are 

 exposed to a 7V/333 solution of acetic acid for 

 twenty minutes, their permeability increases 

 to such an extent, that if they are put into a 

 mixture of 50 c.c. 3 m NaCl + 1 c.c. 2 1/2 m 

 CaClj they sink in less than seven hours 

 (while the normal eggs float in such a solu- 

 tion for three days). If, however, the acetic 

 acid solution is made up in wi/2 NaCl (instead 

 of distilled water) an exposure of the eggs of 

 twenty minutes or more to the acid solution 

 does not injure the membrane. Such eggs will 

 float in 50 c.c. 3 m ISTaCl-f 1 c.c. 2 1/2 m 

 CaCl, three days or longer. By the same 

 method it was ascertained that in the system 

 H3SO,— ??i/2 Na^SO. the action of the acid 

 was more effectively inhibited than in the 

 system HCl — NaCl. From these experiments 

 we are inclined to conclude that the increase 

 in the permeability of the membrane for water 

 and salt under the influence of acids is due to 

 an alteration of the protein constituents of 

 the membrane. 



3. It was found that alcohols also increase 

 the permeability of the membrane of the 

 Fundulus egg for water (and possibly for 

 salts). If eggs are put for sixty minutes into 

 a grammolecular solution of methyl alcohol 

 and then transferred to the test solution (50 

 c.c. 3 m ISTaCl + 2 c.c. 10/8 m CaCh) they will 

 sink in less than eight hours (while the nor- 



*Pfluger's ArcMv, Bd. 75, p. 388, 1899. 

 ° Beutner, Biochemische Zeitsohrift, Bd. 39, 280, 

 1912. 



mal eggs float three days at the surface of 

 such a solution). The relative efficiency of 

 various alcohols for bringing about this in- 

 crease in the permeability of the eggs was as- 

 certained and it was found that each higher 

 alcohol of the series is about three times as 

 efficient as the preceding one. This is the 

 well-known relation indicating effects on 

 lipoids. The facts mentioned sub. 2 and 3 

 agree with the suggestion made by Natanson 

 that cell membranes may be a mosaic of pro- 

 teins and lipoids. 



4. The increase in permeability caused by 

 electrolytes and by alcohols is reversible if the 

 eggs are put into sea water or into a m/2 so- 

 lution of NaCl.+ KCl-fCaCl^ in the usual 

 proportion. If the eggs are put into distilled 

 water they may continue to live, and the fish 

 may hatch, but the increase in permeability is 

 not reversed. It can be shown that distilled 

 water itself increases the permeability of the 

 membrane very slowly. 



Jacques Loeb 



Rockefeller Institute, 

 New York, 



October 22, 1912 



VITAL STAINING OF CHHOMOSOMBS AND THE FUNC- 

 TION AND STRUCTURE OF THE NUCLEUS 



One difficulty in studying protoplasm, par- 

 ticularly of living mitotic figures, is due to 

 the slight differences in the refractive index 

 of the various structures in the living cell. 

 Up to the present, no satisfactory study has 

 been made on the living chromosomes. 



Our studies have been confined chiefly to 

 the testes of the squash bug, grasshoppers and 

 crickets, which are very favorable on account 

 of the large size of their cells, and the clear- 

 ness of the nuclear figures. 



The testes were teased in Ringer's fluid and 

 stained with Janus green (diethylsafraninazo- 

 dimethylanalin) and studied in hanging drops 

 in the Barber moist chamber. By variations 

 in the concentration of the dye beautiful dif- 

 ferential staining of the various cellular ele- 

 ments was obtained. 



Masses of cytoplasmic granules varying in 

 their position in the spermatogonia, sperma- 



