494 



S. O. MAST 



as well as the results obtained in correcting the averages for 

 unequal distribution of energy in the spectrum. The corrected 

 averages are also plotted in figure 4. 



TABLE 3 

 Euglena viridis (positive). Relation between ivave-length and stimulation 



By referring to the two tables mentioned, to table 15, p. 521, 

 and to figure 4 it will be seen that, while the readings for indi- 

 \ddual tests are considerably higher for the negative specimens 

 than they are for the positive ones, due to changes in illumina- 

 tion or to deflection of the path of the organism, discussed else- 

 where, the distribution in the spectrum of the stimulating effect 

 is essentially the same for both. The region of maximum stimu- 

 lation clearly hes between wave-lengths 483 and 493 nn in both, 



» 



Fig. 4 Curves representing the distribution in the spectrum of stimulat- 

 ing efficiency, constructed from data given in table 15. A, Pandorina (negative) ; 

 B, Tandorina (positive); C, blowfly larvae; D, Euglena viridis (negative); E, 

 Euglena viridis (positive) ; F, Euglena tripteris (negative) ; G, Avena sativa (oats 

 seedlings), constructed from data obtained by Blaauw. The circles represent 

 points experimentally established; abscissae, wave-lengths; ordinates, relative 

 stimulating efficiency on the basis of equal energy. 



The curves for Eudorina and Spondylomoriim, not represented in the figure, 

 are in position and form essentially like those for Pandorina; the curve for 

 Chlamydomonas is much like that for blowfly larvae; those for E. gracilis, E. 

 minima, E. granulata, Phacus, Trachelomonas, Gonium, Arenicola, and Lum- 

 bricus are nearly like those for E. viridis and E. tripteris (see table 15). 



