424 BOTANICAL GAZETTE | DECEMBER 
allowed to attain a length of about one centimeter before the bulb was 
transferred to the light cages as hereinafter explained. 
For the purpose of securing light of various wave-lengths, use was 
made of the usual double walled bell glasses prepared as follows: The 
first bell glass was filled with pure water and the second one was 
painted with a very thick coat of lampblack. Two other bell glasses 
were filled with solutions 4 and & respectively. Solution 4 was made 
by adding toa 0.06 » solution of copper sulfate ammonia until the 
precipitate ceased to form. Solution B& consisted of 0.05 7 solution 
of potassium bichromate. 
For each of the experiments there were selected bulbs having roots 
at least one centimeter in length, and as many of these as possible 
were placed under each of the bell glasses prepared as above. The 
bulbs were then left under these glasses, so arranged as to allow of the 
normal respiration taking place, for between two and three days before 
the beginning of the experiment. Roots were then collected from the 
bulbs under each of the glasses at intervals of four hours during the 
twenty-four hours of the day. The tips of the roots thus secured were 
killed in the usual chrom-acetic-acid fixing mixture and imbedded in 
paraffin according to the usual method. The sections were cut 13.34 
thick and stained according to Heidenhain’s iron-alum-haematoxylin 
method.’ 
By means of a very simple method, devised during the investiga- 
tion, it was then possible to count accurately the number of nuclei in 
the process of division and the number resting. A uniform combina- 
tion of ocular, tube length, and objective were used throughout the 
work. In each case the slide was so adjusted as to include in the field 
nearly all the portion of the root tip lying back of the apical cells, the 
field being so placed as to include these apical cells. Within this field 
thus selected it was a relatively simple matter to make very accurate 
counts of the dividing and resting nuclei. Nuclei were classed as 
dividing from the first indication of segregation of the chromatic mat- 
ter in the prophase to the formation of the daughter nuclei at the close 
of the telophase. 
The following tabulation shows the results thus far secured by the us¢ 
of the above described methods applied to this investigation. Each per- 
<a oo given represents the average of nine counts made on three 
sections taken from each of three roots, each of the three roots used being 
* Lee, A. B.: The microtomist’s vade-mecum 175-176. 1896. [4th ed.] 
