EFFECT OF AUTOLIZED YEAST AND PEPTONE 
ON GROWTH OF EXCISED CORN ROOT 
TIPS IN THE DARK’ 
WILLIAM J. ROBBINS 
(WITH EIGHT FIGURES) 
In a previous paper? the writer described a simple method by 
which the excised root tips and stem tips of higher plants can be 
cultivated under sterile conditions, and some experiments in which 
this method was used. These experiments showed that the excised 
root tips of corn would make considerable growth in the dark in a 
sterile nutrient solution containing mineral salts and glucose, and 
but little when no carbohydrate was present. It was found, how- 
ever, that the amount of growth which a corn root tip would make 
under these conditions was limited. If the original root tips were 
grown for ten days or two weeks in the dark in the nutrient solutions 
containing glucose, and then their tips cut off and transferred to 
fresh nutrient solutions, the amount of growth and production of 
secondary roots was decidedly less in the second period than in the 
first, and ceased entirely in the third. The following causes for this 
cessation of growth were suggested: (1) an unbalanced condition of 
the nutrient solution, (2) a deficiency of oxygen, (3) incompleteness 
of the nutrient solution, that is, the lack of some constituent neces- 
sary for continued growth. A consideration of the conditions of the 
experiments and the results obtained suggested that the third pos- 
sibility should be used as a working hypothesis. This assumption 
does not eliminate the possibility that the cessation of growth is 
due to one or both of the other two factors, or that it is due to some 
factor not considered. It is merely used as the basis for further 
experimentation. 
ublished with soem of the Director of the Agricultural Experiment 
Station, , University of Misso The writer cpm eal the kindness of D K. 
Witson in supplying the Longfellow Flint corn u i s investigation, and the 
assistance of Dr. W. E. MANevaL in making the naar caved in experiments 
Mig 
7 Ropsins, W. J., Cultivation of excised root tips and stem tips under sterile 
conditions. Bor. Gaz. 732376-390. 1922 
59] [Botanical Gazette, vol. 74 
