SCIENTIFIC COMMITTEE, JULY 4. 



lxxvii 



deep shade of yellow as they are capable of imparting to wool when 

 mordanted with alum. 



" 2. Populus nigra. — The colouring matter contained in the male cat- 

 kins of the black poplar was not known to the older botanists, or, at any 

 rate, was not referred to by Linnaeus. This is possibly accounted for by 

 the fact that it does not easily impart itself to wool, and could not be 

 used for that purpose by any of the rough-and-ready processes then 

 employed. My attention was first drawn to it by noticing how the foot- 

 pavements in towns were stained by the crushing underfoot of the catkins 

 which had fallen from the tree when in bloom in spring. The stains are 

 a bluish or bluish-green colour, and remain visible for a considerable 

 time. The catkins, or rather the anthers, are of a brilliant red, so that 

 the contrast is very marked. The colour yields itself freely to boiling 

 water to which alum is added, but the salt is not sufficiently acid to 

 produce the full deep red Unlike most colouring matters obtained from 

 flowers, this red is very permanent when exposed to light. The specimen 

 shown was made in 1902, as the label shows. It was placed in light in 

 a north window until the present time. So far as my remembrance goes, 

 it has lost little, if any, of the colour, but the ink with which the label 

 was written has faded to such a degree as to be barely legible. The red 

 colour is also soluble in alcohol. Linnaeus noticed other colours which, 

 although yielding themselves to alcohol and water, were not available for 

 tinctorial purposes, such as the red which the flowers of Hypericum per- 

 foratum yield to alcohol, and the green which the flowers of Delphinium 

 Consolida give to solutions of alum in water. It is curious that the 

 poplar catkins escaped him. 



" 4. Lithospermum officinale. — The old writers, from Linnaeus, were 

 acquainted with the fact that the root of this plant imparts to fats, oils, 

 alcohol, and wax a red colour. They also state that the roots were used 

 by the young women of Sweden to impart a pink colour to their com- 

 plexion. Mr. E. J. Tatum was kind enough to send me some specimens 

 of this plant in April. The colour is confined to the cortical portions of 

 the main roots. It is distributed in patches, which, when rubbed between 

 the fingers, stain them red in the same manner as but to a less degree than 

 the true alkanet-root does. The red colour imparts to solid paraffin a red 

 tint very similar to that from the root of Echium vulgare. The red 

 coloration is more abundant in the roots of Lithospermum than in those 

 of Echium.''' 



Exotic Spider. — Dr. Plowright also sent a specimen of a large spider 

 which had been imported alive in a cold-storage chamber. 



Strawberries Attacked by Millipedes. — Mr. Saunders, F.L.S., reported 

 upon these as follows : — " The ' beast ' attacking the strawberries is one 

 of the 'snake millipedes,' the spotted snake millipede (Julus guttatus). 

 This is a most destructive pest in gardens, since it attacks the roots of 

 various plants. While in the soil it is almost impossible to kill them 

 with any insecticide ; but if a strong solution of common salt or nitrate 

 of soda can be brought to bear on them it will kill them. They may be 

 trapped by burying small slices of mangold, turnip, carrot, or potato 

 near the plants they are feeding on, just below the surface of the soil. 

 These traps should be examined every morning ; a small skewer stuck 



