254 J. J. SKINNER 



in corks and put in the culture bottles, one plant to each bottle, 

 containing 250 cc. of solution. The culture method and manner 

 of securing uniform plants was similar to that described in an 

 earlier volume of this journal. 5 



Solanine being almost insoluble, could be used in only one 

 concentration, namely, a saturated solution. Purified distilled 

 water was used as the culture solution in the first experiments. 

 Four cultures of distilled water as a control and four of water 

 containing the solanine were started March 9 and continued until 

 April 5, when the green weight was taken and recorded. The 

 culture solutions were changed every three days during the experi- 

 ment. The green weight of the four cultures in distilled water 

 was 8 grams and the weight of the four cultures containing sola- 

 nine was 6.6 grams. From this it appeared that there was a slight 

 harmful effect from the solanine. This test, as stated above, was 

 made in distilled water in which the solanine is very difficultly 

 soluble only to the extent of a few parts per million in cold water. 



Other experiments were next made in which the water was 

 boiled to aid in getting the solanine in solution. Three cultures 

 of distilled water as a control and three of the water containing 

 solanine were used. Both the control and the solanine solutions 

 were boiled and after cooling were aerated. The solanine was 

 more soluble in the hot water, so that a saturated solution could 

 be made, which, however, still contained less than fifty parts per 

 million. The plants grew from June 13 to July 1. The solutions, 

 as before, were changed every three days. Two of the solanine 

 plants were killed in this experiment and the one that survived at 

 the end of eighteen days weighed only 0.26 grams while the three 

 control plants in the distilled water weighed 1.84 grams. It 

 is apparent that in these distilled water cultures the solanine had 

 a detrimental effect on the growth of the potato plant. 



The effect of solanine on growth was also tested by using potato 

 soil extracts as culture solutions. The extract of a good soil and 

 a poor soil was used in this test. To obtain any appreciable 

 amount of solanine in solution, the extract had to be boiled as 



6 Skinner, J. J. Water Culture Method For Experimenting With Potatoes. 

 Plant World 2, 249. 1908. 



