INFLUENCE OF DUCTLESS GLAND ON PLANT TISSUES. 1 89 



three different years; and in this connection I am very glad to 

 acknowledge much assistance from three senior students, Miss 

 Helen F. Harvey, Miss Harriet M. Heeman and Miss Gladys 

 Newman. 



METHODS AND RESULTS. 



The experiments were carried out in mid-winter and early 

 spring when the dormant period of onion bulbs is naturally 

 terminating. Material was secured from the open market, from 

 different dealers for successive trials; sound bulbs of medium 

 size, suited to nicely cover the open tops of Naples staining jars 

 of 45 mm. diameter, and 120 c.c. capacity, were selected; care 

 was taken to discard any which already showed root growth. 



The nutrient fluid used in the jars was Pfeffer's solution, made 

 up according to the formula given in Duggar's "Plant Physiol- 

 ogy." : Each experiment consisted of five or more groups of 

 bulbs; to the nutrient fluid in jars supporting them was added 

 desiccated thyroid gland (in tablet form put up by Parke, 

 Davis and Co.) in the following amounts: Group I., I grain; 

 Group II., 0.75 grain; Group III., 0.5 grain; Group IV., 0.25 

 grain; Group V. was the control, which grew on the nutrient 

 solution alone. The solutions were stirred from time to time 

 to secure homogeneity. Some experiments were carried out in a 

 greenhouse affording approximately uniform temperature and 

 humidity; but results obtained under these conditions did not 

 differ from those conducted in the common laboratory environ- 

 ment. 



A further detail may also be mentioned here; it was natural 

 that solutions such as were used, containing organic substances, 

 would gradually become infected with bacteria, no matter how 

 sterile the ingredients at first. This feature of the procedure 



1 Pfeffer's solution as used : 



Calcium nitrate .... . . 4 grams. 



Potassium nitrate ... i 



Magnesium sulfate i 



Potassium dihydrogeii sulfate I 



Potassium chloride 0.5 



Iron chloride trace. 



Water dist 5 liters. 



