The first of these is Tréhala or Tricala, under which name it formed part of the Collection of Materia Medica sent by M. Della Sudda, of Constantinople, to the Paris Exhibition of 1855, and since deposited in the Ecole de Pharmacie in Paris.
Tréhala (fig. 2) consists of cocoons of an ovoid or globular form, about ¾ of an inch in length; their inner surface is composed of a smooth, hard, dusky layer, external to which is a thick, rough, tuberculated coating of a greyish-white colour and earthy appearance. Some of the cocoons have attached to them the remains of the tomentose stalk of the plant upon which they were formed; others have portions of a tomentose spiny leaf built into them; and, more rarely, one finds portions of the flowering heads of the plant, a species of Echinops, similarly enclosed. Many of the cocoons are open at one end and empty; others have a longitudinal aperture, originally closed by the stalk of the plant, and still contain the insect; a few are entirely closed. Specimens of this insect, extracted from the cocoons sent to Paris, were examined in 1856 by my friend Mr. W. Wilson Saunders, who pronounced them to be Larinus maculatus of Faldermann,—a determination also arrived at by M. Jekel from specimens presented by Mr. Loftus to the British Museum. Respecting these latter, one of which is represented in fig. 1, M. Jekel makes the following remarks:—
"Larinus maculatus, Faldermann, Faun. Transcauc. ii. p. 228, 449, tab. 6. f. 10, et iii. p. 198.—Schönh. Gen. et Sp. Curcul. iii. p. 112 et vii. 2. p. 7.—Hochhuth, Bull. Moscou, 1847, No. 2. p. 538 (var. γ).
"Var. γ. Larin. Onopordinis, Sch. loc. cit. iii. p. 111 (excl. synon.).
"Of this species, Mr. Loftus captured several specimens, all of small size: from some of them the pollinosity had been rubbed off, as is represented in the figure by Mr. Ford (vide fig. 1), which shows only a part of the inferior layer of tomentum and the greyish ground of the dorsal and lateral maculæ; the latter, being the most densely coloured in fresh specimens, are always the most persistent. These belong to Schönherr's var. γ, which that author formerly regarded as the Larinus Onopordinis, Fabr. Others of Mr. Loftus's specimens, which are very fresh, belong to var. β; none to the typical variety, which is often larger in size.
"This species has a very extended habitat: I have received it from European Turkey (Frivaldski), Beyrouth, Caucasus, Persia (Dupont), &c. &c.; and it is recorded by Schönherr as also found in Barbary and Portugal.
"This is the insect which proceeds from the rough chalky-looking nidus figured by Mr. Ford. (Vide fig. 2.)"
The entomological question being so far disposed of, I may be permitted a few remarks upon the properties which have obtained for Tréhala a place among drugs and dietetic substances.
The first author who gives any account of the substance is Father Ange, who, in his 'Pharmacopœa Persica[H],' describes it in the following terms:—"Est autem istud medicamentum veluti tragea ex nucleo pistacii integro confecta; nam revera saccharum istud exterius corrugatum et agglomeratum adhæret cuidam nucleo, in quo non fructus, sed vermiculus quidam nigricans Persice C-hezoukek bombycis instar reconditur et moritur."