I s THE BO T. I Nil ' 1 L M. \QA ZTNE. 



[Vol. XXI. No.243. 



Former investigators of the spermatozoids of cycads 1J have 

 usually used \.Q% cane sugar solution (about s / 10 mol. solution) 

 for outside medium with good results. The osmotic pressure 

 of the solution probably corresponds nearly to the turgor ot 

 the spermatozoid-body. In our experiments this solution was 

 also used quite frequently. Then y 2 mol. solutions of cane sugar, 

 dextrose and levulose were tried and the spermatozoids were 

 found to behave just like as in 3 /, mol. cane sugar solution. 

 1 mol. solutions of cane sugar and dextrose (osmotic pressure 

 = [22,4+§j^ atm.]) were also tried. In these cases the spermato- 

 zoids have contracted their bodies by the loss of water and stopped 

 the motion for a short time. Very soon the spermatozoids 

 recover from temporary inactivity and in a few minutes they 

 continue the motion as actively as before. In one case we 

 observed that one of the spermatozoids in 1 mol. solution of 

 dextrose was in motion for nearly five hours. This remarkable 

 behavior of Crcas-spermatozoids in concentrated solutions of 

 sugar is due to the permeability of the plasma membrane 

 for cane sugar and dextrose. We know by the studies of 

 Overton and others that sugars, higher alcohols and amido- 

 acids are almost impenetrable into the plasma membrane of 

 ordinary plant cells. So that such cells undergo permanent 

 plasmolysis in the highly concentrated solution (hyperosmotic 

 solution) of the substances above mentioned. One of us has also 

 observed the similar abnormal permeability of plasma membrane 

 in Isoc£es-spermatozoids. 2) Hexoses (dextrose, levulose etc.) 

 were found to penetrate easily the living plasma membrane of 

 the spermatozoids. This remarkable deviation of the behavior 

 of the spermatozoids in regard to the permeability of the plasma 

 membrane is very interesting from physiological as well as bio- 

 logical standpoints and deserves further investigation. 



In conclusion, we wish to express our sincere' thanks to Profs. 



Iwasaki and IKEDA of Kagoshima, Mr. Haniu of Tanegashima 



and Prof. FujD of Tokyo for the help in securing the material. 



Imperial University, Tokyo. 



u Webber. .Bulletin No. 2 Bureau of Plant Industry, U.S. Dept. Agr., 1901. P. 54. 

 Miyake, Ber. -I. Deutecben. Bot. Gesellsch., Bd. XXIV, 1906, P. SI. 

 l > Bhibata, I. c. p- 694. 



