May 3,1924 
Photoperiodism of Tephrosia Candida 
457 
That the number of pinnae also was affected by the day length would seem to 
be indicated in the count of pinnae of the plants in the A and the B series. In two 
instances, those of the A series had the greater number, in 5 the count was 
equal, and in 17 instances, plants of the B series had a greater number of pinnae 
than did those of the A series. The B series, with a normal day length, had a 
total of 13 per cent more pinnae than the A series, grown in a day of 10-hour 
length. This, however, was not borne out in measurements made January 19, 
and discussed later. (See Table IV.) 
The length of the pinnae was decidedly affected by the day length. In length 
of pinna midway of leaf, the B series exceeded the A series in 21 of the 24 in¬ 
stances, equaled it in one, and was less than it in only two, these latter being in 
case of leaves which were measured January 31'and which had developed in the 
time of shortest day length. In the May, August, and November measurements, 
the difference between the A and the B series amounted to 37, 28, and 22 per cent, 
respectively, but in the January measurements this fell to 2 per cent. The dif¬ 
ference in length of terminal pinna between the A series and the B series was 
04T£ Af£4Si/££0 At AT 24. /922 /U/G./6,/922 MOVJ t /922 J4M 3 /, /923 
C4M//0. r / 2 3^4 S 6' f 7 O 3^/0 // rf'/S 44 /£ /6 /7/9" 99 202/22 2324 s 
^£wSf£L4N7ffo\22 2016 /6 M /2 2220 /S /6 /4 /2 22 20/0 /6 /4 /2 2220/0/6 /4 /2 
OM C*T£ M£ASl/ft£P j 
Fig. 7.—Average internodal length of tallest plant in cans No. 1 to 24, A and B series. A, day length 
reduced to 10 hours. B, normal day 
decided, but not so pronounced as in the pinnae midway of the leaf. The B series 
exceeded the A series in 15 of the 24 instances, equaled it in 5, and was exceeded 
by the A series in only 4 instances, one of which was an estimated measurement 
in lieu of that of a damaged pinna, for which the mean of the leaves above and 
below was taken. The differences for the May, August, and November measure¬ 
ments amounted to 18, 19, and 13 per cent, respectively, while in the January 
measurements this fell to 2 per cent, as in the case of the midway pinna. 
Of the controls for groups 1, 2, and 3, the plants in all cans to No. 13, inclusive, 
flowered in the autumn of 1922, for the time discontinuing further vegetative 
growth. On January 19, 1923, leaf measurements were made on all plants of 
which the controls in these three groups had not flowered, namely the plants in 
cans No. 14 to 18, inclusive, and on their controls. During the 10 weeks preceding 
this date, can No. 16 had received a day artificially shortened to 10 hours, cans 
No. 14 and 17, a day artificially lengthened to 12i hours, and cans No. 15 and 
18, all A series, a day lengthened to 13 J hours. In this period of 10 weeks, the 
normal day had shortened from 11.4 hours to 11 hours, and then lengthened to 
11.2 hours. 
