[We have placed the grains forwarded by our Correspondent in the hands of a skilful horticulturist; and will publish the result.--ED.] _Nacar_ (Vol. v., p. 536.).--This word is not, I believe, a name appropriated to any one particular shell, but is the term used for the pearl-like substance which, in greater or smaller quantities, forms the lining of many shells. This substance, frequently called mother-of-pearl, exhibits in some species a beautiful play of colours, said to be due to a particular arrangement of the particles. The words _naker_ and _nacreous_--with _nacar_ Spanish, _nacchera_ Italian, and _nacre_ French--are given {596} in Webster's _Dictionary_, 2 vols. 4to., London 1832. The beard, or byssus, found in a few genera only, as _Avicula_, _Mytilus_, _Pinna_, and some others, is strong and silky, formed of numerous fibres produced from a gland near the foot of the soft animal, and employed by it to form an attachment to rocks or other objects. In Sicily this is sometimes made into gloves or stockings, more for curiosity than use. A byssus now before me measures six inches in length, is delicately soft and glossy, varying in colour from a rich dark brown to golden yellow, and is nearly as fine as the production of the silk-worm. _Byssine_ is an old name for fine silk. WM. YARRELL. _Mistletoe_ (Vol. v., p. 534.).--Mr. Jesse, in his agreeable and instructive _Scenes and Tales of Country Life_, has devoted a chapter of eight pages to the mistletoe, giving a list of more than forty different species of trees and shrubs upon which this parasitic plant has been found, with many localities. In this list the white, gray, black, and Lombardy poplars are included. The mistletoe is there stated to have been found growing on the oak near Godalming, Surrey; at Penporthleuny, parish of Goitre, Monmouthshire; also on one near Usk, and another at St. Dials near Monmouth. WM. YARRELL.