308 



SCIENCE. 



[N. S. Vol. XVIII. No. 453. 



fication of bases it has been found that all 

 strong bases exert about the same action. 

 The velocity of reaction at 9°. 4 is: 



NaOH 2.31 Sr(OH)a 2.20 



KOH 2.30 Ba(0H)3 2.14 



Ca(OH), 2.29 



The numbers are for 1/40 normal solutions, 

 in which the strong bases may be regarded 

 as completely dissociated." As the dilution 

 of the alkali at which death was produced 

 was much greater the dissociation must have 

 been complete, hence the death must have 

 been caused by the OH and Na or K ions. 

 And as the total growth of the seedlings in 

 KOH solutions is nearly equal to the total 

 growth in NaOH solutions, we can conclude 

 that the toxic effect of Na ions is approxi- 

 mately equal to the toxic effect of K ions. 



From a table of electrical conductivity* 

 the degree of dissociation of HCl at re/256 

 was found to be 98.9, at w/512 it was found 

 to he 99.5. The degree of dissociation of 

 H,SO, at n/256 was found to be 91, at n/512 

 it was found to be 95.6. 



By comparing the dilutions at which the 

 seedlings were found dead with the degree of 

 dissociation given above it will be seen that 

 there is quite a difference between the degrees 

 of dissociation at the strength of the two so- 

 lutions (HCl and H.SOJ. While at the 

 greatest dilution in which the seedlings lived 

 in both solutions the difference is not so great. 

 This difference in the degree of dissociation 

 was manifest in the difference in the total 

 growth of the seedlings in the different solu- 

 tions; the solution less dissociated producing 

 the greater total growth. 



Thus we see that the corn seedling lived 

 and grew in a n/128 solution of KOH and 

 NaOH, and in n/512 solution of HCl and 

 H,SO,. While Kahlenherg and True showed 

 that a seedling of Lupinus alhus L. just lived 

 in «/400 solution of KOH and in n/6,400 

 solution of HCl. This shows that corn seed- 

 lings lived in a solution of KOH more than 

 three times as strong, and in a solution of 

 HCl more than twelve times as strong, as that 



* Arrhenius, I. c, p. 135. 



in which the seedling of Lupinus alhus just 

 lived. 



Although a seedling of a widely different 

 species was used by Kahlenherg and True, 

 yet it is remarkable that the corn seedling 

 should resist the toxic effect of OH ions in a 

 solution three times as concentrated, and that 

 it should resist H ions in another solution 

 twelve times as concentrated. 



If the difference between the effects of the 

 OH ions in one case is three times, why should 

 we not expect the difference between the effects 

 of the H ions in the other case to be about 

 three times also? It seems logical to expect 

 that the ratio between the effects of like solu- 

 tions upon two different seedlings would be 

 about the same in any solution. 



It is my purpose to continue the investiga- 

 tion of this problem to find the exact dilution 

 in which the seedling will just live; and how 

 this death limit varies with different seedlings. 

 Fred A. Loew. 



Agbicultueai, College, Mich., 

 June 16, 1903. 



THE SPONGY TISSUE OF STRASBURGER. 



Many students of the gymnosperms have 

 commented upon the peeviliar structure of the 

 cells immediately surrounding the female 

 gametophyte during the period of its develop- 

 ment. Both Hofmeister* and Strasburgerf 

 believed that two prothallia were formed in 

 those members of the Abietea; which require 

 two years for the maturation of their seeds. 

 They thought that the first or transitory 

 prothallium was characterized by thickened 

 cell-walls and that this cellular body was dis- 

 solved in the spring, giving place to the true 

 or normal prothallium. 



In 1879 Strasburgerf established the fact of 

 the existence of a single prothallium in the 

 Abietese, and described a band of loosened 



* Hofmeister, ' Vergleichende Untersuchungen 

 hoherer Kryptogamen und der Samenbildung der 

 Coniferen,' 1851. 



t Strasburger, ' Die Befruchtung bei den Coni- 

 feren,' 1869. ' Ueber Befruchtung und Zelltheil- 

 ung,' 1878. 



t Strasburger, ' Die Angiospermen und die 

 Gymnospermen,' 1879. 



