clxviii PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



in the seed vessels of Lychnis diurria are those of a small two-winged fly, 

 probably belonging to the family Cecidomyidce. It is very difficult to 

 name these little dipterous grubs unless you can rear the flies." 



Scientific Committee, October 18, 1904. 

 Dr. M. T. Masters, F.E.S., in the Chair, and ten members present. 



Bulbophyllum Wcddelii. — Mr. Odell showed a spray of this Orchid, 

 remarkable for the oscillating character of the labellum. 



Dahlia vircsccnt. — Mr. Saunders, F.L.S., showed some malformed 

 flowers from a cottage garden, upon which Dr. Masters will report. 



Echium, Dye from. — Dr. Plowright sent specimens and the following 

 communication : " For some years past I have been endeavouriug to obtain 

 specimens of Lit hospermum arvense, in order to test its colouring pro- 

 perties ; but I have neither been able myself to meet with specimens, nor 

 have I been able to obtain any frcm my friends. At the suggestion of 

 Mr. E. M. Holmes, I examined the roots of Cynoglossum officinale and 

 Echium vulgare. In the first named I failed to detect any colour ; but 

 in the last named certain specimens contain alkannin in appreciable 

 quantities. As is well known, Echium vulgare favours sandy [or lime- 

 stone] soils, and it is often a brilliant ornament to our sandy lanes and 

 barren places on heaths &c. At times it strays into cultivated light 

 land. I have examined specimens from five localities near King's Lynn, 

 in three of which the Echium roots were devoid of red colour, excepting, 

 perhaps, the barest trace. In the other two the colour was developed in 

 more or less extended patches on the main and secondary roots. The age 

 of the plant does not seem to have much effect upon its production ; but, 

 if anything, it is more abundant in the biennial plant. The two localities 

 which produced it in greatest quantity had this in common. They were 

 both almost pure sand, but received the washings from the main road 

 made of imported granite. In fields, whether manured or not, and in 

 ordinary sandy habitats, the roots were devoid of colour. So were speci- 

 mens growing on roadsides where any flint was employed as road metal. 

 The probable explanation is that the disintegration of the granite yields an 

 appreciable amount of potash. The alkannin is confined to the cortex. 

 It is deposited in the cell-walls in a more or less patchy manner. By 

 treatment with caustic potash the red cells are changed to bright blue. 

 The coloured parts of the roots were treated with spirit of wine and oil of 

 turpentine, both of which dissolved out the alkannin. Fragments of root 

 were treated with white wax, with white hard paraffin, and with lard, to 

 all of which the red colour was'yielded. A disc covered with the alkanme 

 of commerce is also sent. My friend, Rev. H. E. Bishop, of Middleton 

 Vicarage, near King's Lynn, has been successful in growing the true 

 Anckusa [Alkanna) tinctoria in his rockwork garden. He has kindly 

 supplied a specimen, from the root of which the accompanying specimen 

 of lard was coloured pink, as well as a disc of white w r ax. The living 

 plant and its flower were also sent. The red colour of the root is very 

 marked. It contains much larger quantities of the colouring matter, of 

 course, than does the Echium." 



