130 



PRINCIPLES OP PLANT-TERATOLOGY. 



stem, and from chips of the cortex in the Cycad 

 Zamia. 



Groebel figures a case in Streptocarpus Holskii whose 

 axillary shoots had been removed, and from each such 

 axil an adventitious shoot arose bearing leaves in 

 whorls of three instead of two. 



The faculty which some plants, under artificial 

 injury, exhibit for the formation of these adventive 

 shoots has been made use of by bulb-growers ; for 

 instance if a hyacinth-bulb is slit in a certain way at 

 the base through that portion which morphologically 



Pig. 35. — Solatium tuberosum (potato). A system of young tubers 

 sprouting from the pith of the primary one. From a photograph. 



represents the stem, great numbers of small bulbs will 

 be formed along the edges of the slits. 



Again Goebel figures and describes a portion of the 

 parasitic stem of Guscuta glomerata in which a number 

 of endogenous adventitious shoots had arisen in the 

 immediate neighbourhood of the haustoria, and he 

 also states that such were produced artificially by 

 cutting off the upper and lower portions of the stem. 



He also figures a tuber of Corydalis solida which 

 was cut in two : from the cut surface of the lower 

 piece shoots sprouted. 



The " Crown Grail " disease, now known to be caused 

 by Bacterium tumefaciens, gives rise in certain plants 

 to the formation of a dense aggregation of adventitious 



