xlii PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



" It was thought by the appearance of the cell contents that possibly 

 the richness of the soil might account for the trouble. Among many 

 pot experiments, a spray fairly free from ' curl ' and showing no varie- 

 gation was obtained by withholding manure of all kinds, watering well 

 at first and then keeping it dry. This treatment, however, gave no 

 visible result when tried on a large scale. 



" The effect was tried of using varying quantities of artificial and 

 farmyard manure ; of modifying the texture of the soil with ashes, 

 sand, &c. ; of the addition of charcoal, soot, iron, lime, and chalk; of 

 planting affected seedlings in soil from these houses after sterilization 

 by heat, toluene, and formalin ; of transplanting affected plants 

 into a sample of the same soil which had been previously well washed 

 with hot water ; but without throwing light on the cause of the 

 trouble. A healthy seedling planted in well-washed soil from the 

 affected houses, however, remained quite healthy and grew well, 

 though repeated experiments show that when healthy plants are 

 introduced into the untreated soil from the affected houses they at 

 once begin to show the characteristic symptoms. 



" It is worthy of note that a similar case in a greenhouse in another 

 part of the island was treated by the owner in the following manner : — 



" A moveable boiler was brought into the house, and the row 

 thoroughly drenched with water as near the boiling point as possible. 

 The plants died down, but recovered, and the new shoots showed no 

 variegation or curl. 



" None of the affected plants have been seeded down at present. 

 Seed has always been obtained from the same place, and has previously 

 given every satisfaction. 



Suggestions have been made (i) that the trouble is due to 1 defective 

 root action,' resulting in insufficient chlorophyll formation ; (2) that 

 it is due to prolonged growth without a ' rest ' ; (3) that the appear- 

 ance results from planting too deeply ; (4) two experts to whom the 

 owner has submitted specimens attribute the trouble to ' eelworm ' — 

 others can find no trace of insect or fungoid trouble. 



" With regard to No. 2, the owner has previously grown Smilax 

 quite satisfactorily without a 'rest/ and does not agree that this 

 is the cause." 



