1922] ROBBINS—ROOT TIPS 7 
TABLE IV 
EFFECT OF DIFFERENT CONCENTRATIONS OF AUTOLIZED YEAST ON CONTINUED 
GROWTH OF EXCISED CORN ROOTS IN STERILE CULTURE IN DARK 
Ave origi- ig yee gain we no. | Dry weight 
‘Addition to oe ssolu- | No. root tips tel es length n length come per ro roots 
tion+2% g (cm.) "(em ) (gm.) 
1. February 5—February 19 
NOG fo Gt ee ae | 10 a 426° 67 ©.0940 
60 ppm yeasts: 2 seo | Io bars) 12.0 62 0.0840 
200 ppm yeast... 60.585 10 1.8 eG 60 0.0730 
400: DDIM VEASE 5 So. 2b. Io 1.9 13.0 72 0.0820 
800 ppm yeast.......... ike) 1.9 it 6 56 0.0630 
200 ppm gelatine........ 10 oy 10.4 50 0.0624 
2. February 19—March 5 
DSS Gia warden p ee 9 2.3 356 9.6 0.0051 
80 ppm yeast. ......... ine) 1.9 5.907 6.1 0.0056 
200: ppm Yeast) pi...) se) 2.16 =. 71 14.0 0.0116 
400 ppm. Yeast. 4045 os ite) 2.0 5-4 13.2 i: 
OO Ppl Veast. oo. as To ra 4 5-5 9.0 0.0104 
200 pelatine:; 20! fo. 10 1.85 2.14 3:7 0.0044 
3- March 5-March ro 
ON a 9 1.9 0.2 2.9 0.0015 
80 ppm yeast. .2....° ., 8 1.8 4.0 6.5 0.0035 
200: ppm yeast. a 8 2.7 4:2 4.4 0.0043 
#00 ppiy Yeast. oe. 3 8 1.9 3.6 9.6 0.0055 
800 ppm yeast.......... 6 1.6 4.4 10.7 0.0110 
200 pelating... 2.2.5.0: cf 1s O.1 a eg 
4. March ro-April 2 
ppm yeast........... ees oe ares eG 1.15 | 2.2 | 0.0030 
200 Ppm yeast oe. 8 t.9 1.60 0.4 2.0050 
400 ppm yeast. 2.55.0. 5 ; 8 1.6 1.95 3.5 0.0040 
800 ppm yeast.......... 5 1.46 2.60 5.4 0.0046 
SO PEIBTING ig ee i es ee ee ei er ee 
5. April 2-April 16 
80 ppm yeast.......... + 1-8 0.7 ot 
200. DDm yeast. 665.605... | 4 eh 0.5 Oe ee ae a 
400 ppm yeast.......... 2 r.65 a A te gran suten ee 
pm her, 4 1.55 0.8 BODE NG rakes 
February 5—March 19 
tae emis cle alle 9 2.0 20.4 84 0.0898 
jen fom VOR 13 1.93 20.57 97 0.0635 
