I 
A Critical Study of Crown Gall. 
BY 
WILFRID ROBINSON and H. WALKDEN. 
With Plates V and VI and four Figures in the Text. 
C ROWN GALL is a widespread disease occurring on a great variety of 
herbaceous and woody plants in relation to wounds, particularly those 
produced in pruning, grafting, and in the making of cuttings. While of 
considerable economic importance the disease has acquired even greater 
interest on account of the far-reaching comparisons which have been made 
between it and malignant tumours in man by Dr. Erwin F. Smith, 1 to whom 
we owe most of our knowledge of crown gall. 
Tourney ( 34 ) gave the first full description of the disease, while 
Cavara ( 2 ), Tourney, and later Hedgecock ( 7 , 8) proved its infectious 
character by means of extensive inoculations of portions of galls into 
healthy plants. Erwin F. Smith and Townsend ( 19 ) first isolated the 
causal bacterium from the galls on the Paris Daisy (Chrysanthemum frtt- 
tescens , L.) and a large number of other plants, and proved its pathogenicity 
by re-inoculation, naming the organism Bacterium tumefacie ns, Smith and 
Townsend. They studied its cultural characters fully, and since that time 
E. F. Smith (19 to 32 ) has carried out much experimental work on crown gall, 
and we are indebted to his activity for the accumulation of a vast amount of 
extraordinarily interesting and suggestive detail regarding the disease. He 
also early instituted comparisons between the crown gall disease of plants and 
malignant tumours in man; and a great deal of his experimental work has 
1 Since completing our paper we have seen a recent paper by Smith on Appositional Growth in 
Crown-gall Tumours and in Cancers, Journ. Cancer Research, vii, 1922. In this Smith describes and 
figures the development of tumour-tissue by the subdivision of normal parenchyma cells. He states 
that a narrow strand of tumour tissue is converted into an extension of the tumour as a result of the 
stimulating effect of the bacteria either within the cells or acting at a distance. He now' expresses 
the opinion that most, if not all, tumour-strands originate in this way, thus receding from his earlier 
position that tumour-strands and secondary galls originate by the intrusive growth or infiltration of 
tumour-tissue. He still maintains, however, that the tumour is due to an ‘ intracellular schizo- 
mycete \ 
(Annals of Botany, Vol. XXXVII. No. CXLVI. April, 1923.} 
