104 



MISSOURI BOTANICAL GARDEN. 



The date seed has long furnished material for studies 

 begun with Malpighi, later continued by Sachs, whose work 

 is fundamental, and followed by several others whose work 

 will be mentioned beyond. This has been due in part to 

 the ease of obtaining material and the conspicuousness of 



th 



devel 



f 



not the least important contributions in this field having 

 been made by Americans, The positive evidence thus gained 

 is of value not only in interpreting what goes forward dur- 

 ing germination, but also during embryogeny. Working 



m 



begun, we are able 



many details for which otherwise 



lative explanation 



advanced 



Methods. 



Material was gathered on alternate weeks, from the timo 

 of pollination till maturity, from one of the two races and 

 preserved in three series, one in a watery solution of copper 

 acetate, as recommended by Strasburger, one in chrom-acetic 

 fluid, followed by alcohol, the third in alcohol-acetic, (2:1). 

 For examination, free-hand sections were used, except in 

 earlier stages, in which it was necessary to use microtome 



ithods for the determination of minutiae of structure. 



m 



treated 



or chlorid). 



After long standing in copper acetate, the material con- 



tained 



many 



a considerable amount 



metall 



copper, either within the tissues, on its surface or in the 

 fluid. This was evidently due to the reduction of the copper 

 salt, chiefly, it seems probable, by the invert sugars present. 

 The possible source of error, due to the presence of tannin, 

 was excluded by the use of ethyl nitrite, on a small but 

 satisfactory series of material prepared for me during the 

 spring of 1910 by Dr. Vinson at my request. This check 

 material showed that my observations on the copper acetate 

 preparations were correct. This is of considerable impor- 



