the Effect of Formaldehyde on Living Plants. 
43i 
Experimental Results. 
Determination of the true Dry Weight of Desiccated Seeds. 
The seeds were weighed out on to tared watch-glasses, heated for 
several hours to 8o°-ioo°, cooled in a calcium chloride desiccator and 
weighed. 
Results : — 
Expt. 1. Expt. 2. Expt. 3. 
Original weight 0-4010 grm. 
Final weight 0*3860 „ 
Water lost 3*74 % 
0*4010 grm. 
0*3855 >> 
3*62 % 
0*3980 grm. 
0*3830 „ 
3*77 % 
Mean amount of water lost = 3*71 % 
This mean value was used in calculating the dry weight of the seeds in 
the respiration experiments. In the later experiments two or more weighed 
quantities of ground seeds were heated, simultaneously with the cultures, to 
give their loss in weight on heating. This was necessary because of the 
impossibility of exactly regulating the temperature of the oven, and also 
because, after prolonged heating, some charring was produced. 
Determination of the Gain in Dry Weight due to Hydrolysis. 
In order to find the true loss in dry weight due to respiration, it was 
necessary first to know the total gain in weight due to hydrolysis of sugars, 
&c., during germination. This was not easy to determine, and even when 
concordant results were finally obtained, they can only roughly indicate the 
real value in the plant, because an inorganic hydrolysing agent was used 
whose action may differ widely from that of the enzymes in the germinating 
seeds. 
The mustard seeds were found to contain no starch, but a considerable 
reserve of fats and proteins, together with the glucoside of mustard oil. 
On hydrolysing them in the ordinary way with io % HClAq and 
evaporating off the acid over a water-bath, so much charring of the sugars 
occurred that it was impossible to obtain concordant results. Besides this, 
the uncharred sugars were so deliquescent that they formed syrupy drops 
even in the desiccator. Experiments were made in which the HClAq 
was distilled off from a weighed retort in vacuo at temperatures of 20° to 
30°. Here less charring occurred, but it was necessary to dry the weighed 
vessel for some hours in a current of dry air at 50°, and the action of the 
remaining HC 1 vapour on the seeds at this temperature seemed to induce 
further charring. The results were more nearly concordant, but were not 
considered sufficiently satisfactory. 
The final method employed was to digest the seeds, previously ground 
to powder in a dry pestle and mortar, with 10 c.c. of 1 % HClAq for five 
to eight hours, and then to allow the mixture to stand for two or three 
weeks in a vacuum desiccator over stick potash until all signs of moisture 
