4] 



TONOTAXIS 



were repelled. The numbers at the heads of the columns are 



the different values of n in the formula, 



n 



1000 



MW%. Since 



the different solutions were made up on the basis of molecular 

 weights, all solutions of a given concentration contained the 

 same number of molecules. 



TABLE XII 



From this table it appears that, as a rule, solutions of y 

 MW % and over are repelled, while those of T ^Vo or under, 

 except in the case of KCN, permit the free migration of the 

 bacteria into the tube. 



In the case of those substances whose isotonic coefficient is 

 4, solutions of y oVo MW % anc l over always repel, and those of 

 YoVo i 11 the majority of cases permit free migration. In the 

 case of those substances whose isotonic coefficient is 2, solutions 

 of over YJ^-O MW % repel, and those of under yo^o" usually 

 permit free migration. The solutions at which repulsion just 

 occurs in the three cases are in the ratio 10 : 7 : 6 ; which is 

 nearly the same ratio as the reciprocals of the isotonic coef- 

 ficients, which, multiplied by 2 run, 10 : 6.6 : 5. Thus the 

 conclusion seems justified that the repelling action of these 

 substances is proportional to their isotonic coefficients, and is, 

 therefore, probably osmotic in its nature. 



In a second work, MASSART ('91) has studied this matter 

 with the aid of new methods. A drop of sea water containing 

 bacteria is prepared as before, on a cardboard ring, but, in place 



