178 Ingvar Jorgensen and Walter Stiles. 
Table XIV. 
Relation between Assimilatory Activity and Number of Chloroplasts. 
Species. 
Assimilatory 
Activity 
per unit area. 
Number of 
Chloroplasts 
per unit area. 
Tropoeolum majus 
100 
100 
Phaseolus multiflorus. 
72 
64 
Ricinus communis . 
118-5 
120 
Helianthus annuus . 
124-5 
122 
But of course there is no evidence or even probability that all 
chloroplasts contain the same amount of chlorophyll, so that this 
attempt to correlate assimilatory activity with quantity of chloro¬ 
phyll is extremely crude. 
While we have no criticisms to offer in regard to Willstatter’s 
chemical analysis of the pigments, it appears from his preliminary 
account that the experimental arrangements in his assimilation 
experiments may be open to considerable criticism. As, however, 
he promises a detailed paper in which “ many remarkable details 
in the experimental arrangement” are to be described, it seems 
desirable to defer such criticism to a later period. 
The main principle of his method of experimentation is the 
same as that used by earlier workers, e.g., Kreusler (1885-1890) 
and Blackman. The noteworthy features of Willstatter’s method 
are: 
(1) The carbon dioxide is determined by weight in an absorption 
apparatus. 
(2) The high intensity of illumination. He uses a \ watt Osram 
lamp of 3000 candle power at 15-25 cm. distance from the leaf 
chamber (corresponding to a light intensity of 48,000 to 130,000 lux). 
(3) The rapid stream of carbon dioxide (4-5 litres per hour). 
(4) The method of temperature measurement. The temperature 
of thecas in the leaf chamber is measured (presumably by a mercury 
thermometer); it is obvious, in view of Blackman’s experiments, 
that this is indeed very unsatisfactory, particularly when such high 
light intensities are employed. 
The experimental conditions used by Willstatter are such “ that 
the assimilation of a normal well assimilating leaf cannot be increased 
by increasing the carbon-dioxide concentration or the light intensity .” 
The temperature, which is kept constant, generally 25°C, is 
“ favourable to assimilation.” 
