MOTOR RESPONSES 



289 



and other flagellates. Strasburger (1878) concluded that stimulation is 

 confined to violet, indigo, and blue in the solar spectrum, with the maxi- 

 mum in the indigo. Engelmann (1882) maintains that for Euglena the 

 maximum is in the blue between 470 m\x and 490 m^, and Loeb and 



Figure 102. Curves representing the distribution in the spectrum of stimulating 

 efficiency, constructed from data given in Table 15 (See Mast 1917). A, Pandorina (nega- 

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

 Euglena viridis (positive) F, Euglena tripteris (negative) ; G, Avena sativa (oat seed- 

 lings). (Constructed from data obtained by Blaauw.) The circles represent points experi- 

 mentally established abscissae, wave lengths ; ordinates, relative stimulating efficiency on 

 the basis of equal energy. The curves for Eudorina and Spondylomorum, 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 Euglena gracilis, E. 

 minima, E. granulata, Phacus, Trachelomonas, Gonium, Arenicola, and Lumbricus are 

 nearly like those for E. viridis and E. tripteris. (After Mast, 1917.) 



Maxwell (1910) assert that in the carbon-arc spectrum it is between 460 

 and 510 m\i. The unequal distribution of energy in the spectrum was not 

 considered in these conclusions. Mast (1917) made corrections for un- 

 equal distribution of energy and ascertained the relative stimulating effi- 

 ciency of negative and positive orientation at intervals of 10 )?i\\ through- 



