23 



the grains by spreading them on wet filterpaper. The 

 germination then takes place much more regularly. In 

 order to keep the filterpaper wet, it was laid on a flat 

 glass dish, turned upside down in the earthen ware dish. 

 The latter was filled with water so that the filterpaper 

 was always in contact with the water. The earthen ware 

 dish was covered with a second one. 



After two days, germination had proceeded far enough 

 and uniformly enough, so that I could plant about 50o/o 

 of the grains. This was done in the same vessels ofzinc, 

 measuring 20 x 3 x 3 cm., that had been used by 

 Blaauw and also by Mrs. Ru tten-Pekelharing. In 

 most cases I planted not one, but two rows in every 

 vessel so that each vessel contained 30 to 36 plants. 

 After two days in the dark in wooden boxes of 50 x 30 x 

 20 cm, doubly lined with dark cloth and covered in the 

 same way, the coleoptiles had reached a sufficient length 

 (10 to 35 mm) to be used in the experiments. Spécimens 

 that were not quite straight or plants of which the hypo- 

 cotyl had developed, had been previously removed and 

 for convenience sake the number was often reduced to 

 25 in each vessel. In addition the vessels were watered 

 by means of a small spray on the morning of the second day. 



The greatest difficulty encountered in growing the 

 seedlings was the growing out of the hypocotyl. In the 

 beginning this scarcely ever happened, later on (after 

 about March 1910) it gave me much trouble. Again and 

 again I had to destroy whole batches for this cause. When 

 the hypocotyl grows out, it grows in the direction it has 

 underground without altering this direction as it is not 

 geotropically sensitive. Consequently it mostly protrudes 

 obliquely from the soil and so the coleoptile also slants. 

 The latter afterwards bends itself geotropically and so 

 it is of no use for the experiment. 



