50 INFLUENCE OF CHEMICALS 



73. Effect of Chloroform upon Mimosa. Place a sponge sat- 

 urated with chloroform near a vigorous expanded specimen of 

 Mimosa and cover with a bell-jar, being careful not to give the 

 plant a mechanical shock. Does the action of the vapor cause 

 movement ? After ten minutes remove the jar and apply shock 

 stimuli. Determine the length of the period necessary for the 

 plant to. recover irritability to mechanical stimuli. Allow a second 

 specimen to remain under the bell-jar for a day with chloroform 

 vapor and note results. 



74. Effect of Chloroform upon Oxalis Leaves. Add i cc. of 

 chloroform to 200 cc. of water in a bottle and shake. Cut a leaf ' 

 of Oxalis into narrow strips and place them in the liquid. The 

 length of time necessary for the chloroform to kill the tissues may 

 be determined accurately since the leaf assumes a dingy yellow 

 color upon death. 



75. Degree of Molecular Complexity and Intensity of Poison- 

 ous Action. The series of alcohols of the lower paraffins affords 

 a convenient means of demonstration of the correspondence of 

 molecular complexity and intensity of poisonous action. The 

 formulae for some of the alcohols are as follows : 



Methyl, H— CH 2 OH. 



Ethyl, CH 3 — CH 2 OH. 



Propyl; norm., CH 3 .CH 2 — CH 2 OH. 



Propyl ; iso., CH 3 — CH.OH— CH 3 . 



Butyl ; norm., CH 3 .CH 2 .CH 2 .— CH 2 OH. 



Butyl ; iso, £JJ 3 >CH— CH 2 OH. 



Butyl; tertiary, £JJ 3 >COH— CH 3 . 



Amyl ; norm., CH 3 .CH 2 .CH 2 .CH 2 .— CH 2 OH. 



Prepare two series of six small dishes in which colonies of 

 Spirogyra may be grown. Make solutions of ethyl alcohol and 

 of methyl alcohol containing the following concentrations ; normal, 

 \ normal, \ normal, \ normal, \ normal and ^ normal. Nor- 



