199 
Parr .— The Response of Pilobolus to Light . 
Trondle (1910) in his effort to bring the results of his work concerning 
the relation of permeability to light intensity into conformity with the 
Talbot law has developed a formula deserving attention. His data show 
that the product of the reaction time less a constant (k) multiplied by the 
intensity is always the same, expressed mathematically thus: 
i 1 (t 1 -k) = i 2 ( t ,~k). 
The present series of data tested by this formula is given in Table X, 
where I n and T t = intensity for a given wave-length, t n and t r = presentation 
times for ‘ second positive ’ reaction in the same wave-length from the 
Nernst and the tungsten lamps respectively. Here, too, there is seen to 
be a gradual decrease in the constant k from red to violet. Again, 
multiplying the variable constant in each case by the square root of the 
frequency, a very fair constant result is obtained, as shown in the last 
column. 
Table IX. 
Wave¬ 
length. 
708 
667 
631 
612 
589 
585 
54 ° 
52 2 
496 
470 
464 
437 
414 
398 
Energy in ergs Presentation /, 
per sec. per cm* time in min. 52 A log — 
Fre ¬ 
quency - 
/n 
E 
St 
log 10 /» 
log 10 T t 
, L 
log 10 7 
J t 
A 
v/ 
A V/. 
424 
I-6l6 
7.9S0 
78 
68 
0-2084 
0-9020 
0-6936 
10 
I 4 ' 4 l 
20*6 
297 
450 
1-097 
5.760 
76 
66-5 
0-0302 
0-7604 
0-7302 
9*5 
13-01 
21-2 
276 
472 
O.647 
5-843 
75 
64‘5 
1-8109 
0-7666 
o -9557 
9*5 
9*93 
21-7 
2I 5 
494 
o -344 
3-109 
73 
64 
1-5366 
0-4926 
0-9560 * 
9 
9 * 4 i 
2 2-2 
209 
509 
0-305 
2-480 
72 
63 
1-4843 
o *3945 
0-9102 
9 
9-88 
22-5 . 
222 
5 12 
0-295 
2-360 
72 
63 
1-4698 
0-3729 
0-9031 
9 
9-96 
22-6 
225 
556 
0-149 
1*350 
69 
60 
1-1732 
0* 1303 
0-9571 
9 
9*40 
23-6 
223 
574 
0-128 
1-050 
67-5 
59 
1-1072 
0*0212 
0-9140 
8*5 
9*30 
23-9 
222 
607 
0-097 
o -735 
65 
57 
2*9868 
1-8629 
0-8761 
8 
9- T 3 
24-6 
224 
638 
0-077 
o-686 
63 
55 
2-8865 
1*8363 
0-9498 
8 
8-42 
25*2 
212 
648 
0-063 
0-578 
62 
55 
2.7993 
1-7622 
0-9629 
7 
7*27 
25*4 
185 
686 
0-056 
0-364 
60 
54 
2-7482 
1*5611 
0-8129 
6 
7*38 
26-3 
194 
738 
*0-038 
0-145 
56 
5i 
2*5797 
r-l6i3 
0-5816 
5 
8*59 
27-1 
233 
753 
0-032 
0-130 
55 
5° 
2-5052 
I-H 39 
0-6087 
5 
8-21 
27-4 
225 
* This value is high according to Coblentz. 
Table X. 
Energy in Presentation 
ergs per sec. time in 
per cm .' 1 mins. 
Wave¬ 
length. 
Fre¬ 
quency. 
/- 
T t . 
4 - 
t T . 
708 
424 
20-6 
3 - 6 i 6 
7-98o 
78 
68 
667 
450 
2 1-2 
1*097 
5760 
76 
66-5 
631 
472 
21-7 
0-647 
5*843 
75 
6 4*5 
612 
494 
22-2 
0*344 
3-109 
73 
64 
589 
509 
22-5 
0-305 
2-480 
72 
63 
585 
522 
22-6 
0-295 
2-360 
72 
63 
540 
556 
23-6 
0-149 
1*350 
69 
60 
523 
574 
23*9 
0-128 
1-050 
67*5 
59 
496 
607 
24-6 
0-097 
0*735 
65 
57 
470 
638 
25-2 
0-077 
o-686 
63 
55 
464 
648 
25-4* 
0-063 
0-578 
62 
55 
437 
686 
26*3 
0*056 
0-364 
60 
54 
4*4 
738 
2 7 -l 
0-038 
0-145 
5 6 
5 1 
398 
753 
27-4 
0-032 
0-130 
55- 
50 
I. «.-*) = A (ft-i). 
K AWf. 
I‘6i6 (78-0 — k) = 7*988 (68*o-£) 65*4 1347 
1*097 (76-0 —£) = 6.514 (66.5-k) 65-5 1389 
0-647 (75*o-^ = 5*843 (64-5-£) 63-2 1371 
0*344 (73*0-*) = 3-47 3 (64-0-£) 63-0 1398 
0-305 (72-0 —= 2*480 (63-0 —£) 62-2 1399 
0-295 (7 2 -o-/5) = 2-360 (63*0 —k) 61-7 1394 
0-149 (69-0-^) = 1-350 (6o-o-£) 58-7 1385 
0-128 (67*5-A) = 1*050 (59-0 —£) 58-9 1407 
0-097 (65-0-£) = 0-644 (57-o-^) 55*5 ^65 
0-077 (63-0—£) = o-686 (55-0—$; 55-6 1401 
0*063 (62*0-^) = 0-578 (55*°-^) 54* 1 J 374 
0-056 (6o-o~£) = 0-364 (54-0-^) 52*9 1391 
0-038 (56-0-/^) = 0-145 (5I-0-/&) 49-2 1333 
0-032 (55-0 -k) = 0-130 (50-0-£) 48-3 1323 
