148 J'UOF. ATTFIELD — POISONS NOT ALWAYS rOISONS. 



plant termed henbane is infused or boiled in water, the juice 

 is pressed out of it, and the watery parts are all boiled away ; the 

 residue is the common medicine, extract of henbane. Now I think 

 you will see that if any soluble substance, such as a piece of sugar, 

 is dissolved in such an infusion, decoction, or juice, — say a lump 

 of sugar in ordinary infusion of tea, — and if you stir the liquid 

 well and boil it down until all the water is gone, the extract which 

 remains will contain in every portion of it a particle of sugar. So 

 with infusions of such poisonous plants as henbane, belladonna, 

 and others. "When infusions, decoctions, or juices of these plants 

 have been evaporated down, the water all boiled away, and you 

 get remaining an extract, I think you cannot conceive any particle 

 of that extract which does not contain a portion of the poisonous 

 principles of those plants. The bearing of these remarks will be 

 obvious to you directly. 



Amongst the extracts I examined, was that of a very poisonous 

 plant, Strychnos Nux-vomica, from which is derived that powerful 

 poison strychnine. If you infuse the seeds of Strychnos JSfux- 

 Tomica in water, you will dissolve out of them their strychnine, 

 and if then, throwing away the exhausted seeds, you boil down 

 what is left, you will have an " extract of nux- vomica," and the 

 whole of that extract, even the most minute portion of it, will 

 contain strychnine. On such extract I found, especially on exami- 

 nation with a lens, numbers of mites. These mites had obviously 

 eaten, nay, were actually eating, the extract. The conclusion was 

 irresistible that they had eaten and were eating strychnine. They 

 were sufficiently like ordinary cheese mites for me to infer that 

 they really were mites, and belonged to the insect-like class of 

 Arachnida, which having eight legs instead of six are not true 

 insects. These little animals — though, even to my unpractised 

 eye, obviously mites — did not resemble ordinary cheese-mites very 

 closely. I examined some other extracts, and the extract of 

 colocynth, a well-known medicine, furnished me some mites. I 

 also obtained some from other sources, and found that the different 

 communities of mites differed considerably. 



With the object of ascertaining the exact nature of the different 

 mites, I submitted specimens to Professor Busk, and he came to the 

 conclusion that there were three mites previously both generically 

 and specifically unknown — that I had, in short, by an accident, 

 discovered three new species of animals. Two of them probably 

 belonged, he said, to the same genus, but the other did not. So that 

 I had even discovered two new genera. Under some circumstances, 

 that would be a grand thing to do ; but in this case the honour was 

 almost thrust before my eyes, or, if achieved, was an honour that 

 I think could be achieved by any one who possessed a magnifying 

 glass, not to say a microscope, and had interest enough to examine 

 some of the many things common on the road- side, in the garden, or 

 even in their own household. Before I leave the Natural History 

 part of the matter I should like ju.st to tell you, what Mr. Busk 

 told me, that there are two or three special points of interest about 



