( J 80 ) 



the leaf-tips extremely small wounds were made by means of the 

 sterilised, very line point of an injection syringe. 2). The same was 

 done after the point had lirst been stuck into yellow vesicles, caused 

 by the scale-insects. 3). A number of yellow and thickened leaf-tips 

 were ground in a mortar and a very small portion of the so obtained 

 pulp, mixed with some diluted glycerin, injected in several places 

 in leaf-tips. 4). The same operation as in 3 was applied after the 

 pulp had first been heated to 100° C. 



The result was exactly the same in all cases. 



After some ten days small, brown specks were visible in the 

 wounded places, which afterwards could still increase somewhat in 

 size. A month after the wounding the brown specks had become 

 surrounded by a very thin, more or less transparent, yellow margin. 

 The brown specks were formed by the cells which had died in con- 

 sequence of the wounding, and the walls of which had turned brown. 

 In the yellow margin a complex was found of relatively small cells, 

 leaving no intercellular cavities. These cells had thick walls and 

 their protoplast still contained remnants of the chlorophyl grains. 

 The complex was formed by hyperplasia of the whole mesophyl. 

 On the border between this complex and the normal tissue some 

 cells of the spongy parenchyma had become greatly enlarged, their 

 chloroplasts having become disorganised. After another month it was 

 noticed that the leaf-tips in the neighbourhood of the wounded spots 

 assumed a somewhat yellow colour, which gradually became more 

 and more distinct. Microscopically it could be stated that where 

 externally this yellow discoloration was visible, the tissue round the 

 wounded spots had undergone precisely the same changes as take 

 place round the yellow vesicles, caused by the scale-insects, namely 

 a general hypertrophy of the cells of the spongy parenchyma, while 

 here and there even a partition wall had already been formed in 

 the enlarged cells. 



As was stated above, this result was obtained in all cases, also 

 in those in which small wounds had been made without anything 

 else. From which we may conclude that the leaf of Gnetum Gnemon 

 may be stimulated to the formation of intumescences and hence of 

 adventitious buds by wounding, provided this is very light and that 

 consequently the process must be regarded as a reaction on a 

 wound stimulus. 



In a disease of carnations which also consists in the formation of 

 a sort of intumescences ') and for which it has been shown by 



!) H. V. SCHRENK 1. C. p. 39. 



