scil [PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



known as much as possible, as no gardeners about here seem to know of 

 its being poisonous, and the roots are being dug up in all directions." 

 Mr. E. M. Holmes. F.L.S., writes as follows : "I can find no mention in 

 books, at present, of the Phaseolus multijlorus (coccin-eus) being poisonous, 

 but a nearly allied species. P. lunatus, with smaller flowers and crescent- 

 shaped pods, is known to be poisonous to cattle. According to the 1 Agric. 

 Ledger,' 1905, No. 2, p. 13. 1 a number of cases in which cattle had been 

 poisoned as a result of eating the plant had been recorded in Mauritius, 

 and in 1898 Mr. Bonaine showed that the whole plant produced prussic 

 acid when ground up with water, the larger amount being obtainable 

 from the seeds.' These beans have been investigated at the Laboratory 

 of the Imperial Institute, and it has been proved that they yield (before 

 being boiled, presumably) an average of 0*009 of .prussic acid, but that 

 amount may vary very widely, the cause of such variation being unknown 

 (I.e., p. 16. See 'Bull, of Imperial Institute,' 1903, vol. i. pp. 16-115). 

 The prussic acid does not pre-exist, but is formed by the decomposition 

 of a glucoside called phaseolunatin, by means of an enzyme, probably 

 identical with the emulsion of bitter almonds. As the ferment is con- 

 tained in separate cells, it is only when the plant is bruised or injured 

 that the contents of the cells come in contact, and it is necessary that 

 water should be present in order for the poison to be developed. The 

 same arrangement occurs in the cherry laurel (Primus Laurocerasus), 

 so that the leaves may be dried and then powdered, and no prussic acid is 

 fornie,d until the powder is moistened, although it is readily given off 

 when the fresh leaves (which contain water) are bruised, as every 

 entomologist knows. This case of poisoning raises a very interesting 

 point with regard to this familiar vegetable, viz. : 1 will the bruised fresh 

 pods of the scarlet runner yield prussic acid, and will the air-dried seeds 

 do the same ? ' It is quite possible that they may be poisonous if eaten 

 before being boiled, since boiling would destroy the enzyme, or render it 

 inactive, so that the prussic acid would not be developed in the boiled 

 pods. I may also point out that Phaseolus aconitifolius, Linn., is used 

 as fedder for cattle, although the root is stated by Royle to be narcotic 

 (Watt, 1 Diet. Ec. Prod. India,' vi. pt. 1. p. 185). The seeds of P. semi- 

 erectus, Linn., are used in the West Indies as a fish poison (Rosenthal, 

 • PI. Diap.' p. '1019)." 



Scientific Committee. December 5, 1905. 

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



Lindley Library. — Dr. Masters remarked on the fact that this was 

 the first time the Committee had met in the room set apart for the 

 Lindley Library, and stated that both the purchase of J he library and the 

 formation of the Scientific Committee were the outcome of the Botanical 

 Congress of 1866, and were the two objects pointed out by Prof. A. de 

 Candolle as desirable of attainment in the openiug address at that con- 

 gress. 



Troublesome Weed. — An inquiry was received from Las Palmas 

 regarding a weed known as 1 juncia ' or 1 chufas,' which is exceedingly 



