difficult to discern as they are extremely fine, and lie in the direction of this spiral.

The anal orifice lies on the left side of the body close under the peristome margin. It is usually seen as a round bladder, shown by the finer marking at z, Plate I., Fig. 2, and distinctly visible at z, Plate II., Fig. 2, where the excrementitious matter is pouring out through a wide round opening in the body wall of the creature, as Stein states he has frequently seen slowly accomplished. After the contents of the anal vesicle are ejected, the aperture closes, and scarcely a trace of it is visible.

The contractile vesicle is shown in Plate I., Fig. 2,c; it lies below the anus, a little deeper and somewhat nearer the ventral side, and doubtlessly pours its contents into the anus, and is fed by a long canal which extends towards the hinder part of the body on the left side, and nearer the ventral than the dorsal side, Plate I., Fig. 1, g; Fig. 9, 7. This canal is scarcely ever visible throughout its whole length, but is seen in various lengths interrupted at intervals. Frequently it remains invisible for a long time. When considerable unbroken lengths appear, they indicate a winding course, with longer or shorter spindle-shaped enlargements, or with a strong expansion at either end. The gradual flow towards the contractile vesicle of fluids collected from the tissues of the body, and their entrance into the vesicle may be clearly seen, especially when the animals are elongated.

The nucleus is very constant in form in the same species, and affords the best specific distinction. It consists either in a string of not very numerous and similar segments, as in Plate I., Figs. 1 and 9, n, or a twisted thread-like band, Plate II., Fig. 1, n, or a simple round body (as in Stentors igneus, niger, and multiformis).

Multiplication by division follows the same rule in all species, and occurs transversely, affording many points of resemblance to what takes place in other infusoria. The process of sexual reproduction, Stein says, is not yet sufficiently elucidated. There are, indeed, various accounts by different observers, but they are strangely opposed to each other except as regards the well-established fact of conjugation.

The longitudinal stripes which characterize the Stentors are sharply defined, and run from the margin of the peristome in regular order, without interruption, to the hindmost portion of the body. In many positions, such as those which afford a side view of the body when the peristome is completely enfolded, the course of these bands may be distinctly observed right up to the oral ciliary wreath, and

when the peristome is folded up, and inclined strongly towards the axis of the body, the bands are seen sharply divided, with toothed edges slightly inclined inwards, and a narrow stripeless zone appears just under the oral wreath.

The width of the striped bands follows that of the body, being narrower or wider, as the body varies. In fully outstretched creatures with expanded peristome, the striped bands have the greatest 'breadth in front, and they grow so narrow hindwards that they can scarcely be followed when the posterior end is reduced to a stiff style, which often presents a smooth surface. As soon, however, as the animals noticeably shorten themselves, and become top-shaped, or pear-shaped, or merely globular, the striped bands become plain from end to end. But it will frequently happen that one or other of the stripes does not reach the hinder extremity, but wedges itself between its neighbours, and disappears. Sometimes such a stripe will reappear a little lower, widening or shortening, adjacent stripes on one side as it continues its course. On different parts of the body it may often be seen that two adjacent stripes are parted for a greater or less interval, and that the cleft is filled up with from two to four stripes, pointed at both ends. In such cases a rupture has apparently taken place, and the outpouring sarcode has organized itself into the shorter intermediate stripes. For illustration of interrupted stripes, see Plate II., Fig. 8.

In fully outstretched animals regular transverse stripes are visible, and most plainly so on the broadest part. In strongly contracted individuals the body stripes form longitudinal raised ribs with fine cross elevations (querhöcken). Many Stentors, such as Ceruleus and Rösellii, exhibit in a state of medium contraction a peculiar condition of the stripes of the hinder portion. These stripes are bounded by regularly curved and finely wriggling lines, sharply exhibited when as is often the case, there is a large vacuole at that portion of the body. Lieberkuhn first observed these lines, which he took for veritable muscular threads (see Plate II., Fig. 7), and E. Weber also thought them muscular fibres in a state of rest. If the end of the body is flattened these wriggling lines change into the ordinary long furrows, and appear only as transparent threads bounded by contour lines, which Stein considers only folds of the cuticle.

The contractions and expansions of Stentors always follow the direction of the striped bands, and the varying forms of the body result from their lengthenings or shortenings.

Stein proceeds to remark on the different degree of rapidity with

which the Stentors change their shape. He also describes long nonvibratile bristles as regularly placed amongst the body cilia of many individuals, and which were first noticed by Lachmann. These bristles are longer or shorter, and suddenly spring up in places where no appearance of them was previously seen, and in a similar way they vanish, leaving no trace behind. At their base, or embedded in the tissues of the body no capsular organ can be seen from which they could emerge. Stein regards them as resembling the pseudopodial prolongations, which serve to fix the hinder extremity, and says without doubt they are organs of touch. These bristles are shown in Plate II., Fig. 1.

We shall continue the subject of Stentors in our next number.

SOURCES OF COPAL.

BY JOHN R. JACKSON, A.L.S.,

Curator of the Museum, Royal Gardens, Kew.

COPAL is an article well known to commercial men, but the source or sources whence it is derived are very imperfectly known to botanists. The term copal is so generally applied to the better or clearer kinds of resin, used for varnish-making, that it seems after all to be a somewhat indefinite term, yet copal, anime. and dammar, are distinct commercial names for very distinct resins, and the sources of all of them are more or less shrouded in mystery, indeed there seems to be a similiar chronic doubt with many of our imported resins, for olibanum and some others of that class have long been subjects of inquiry amongst botanists and pharmaceutists, not only in England but in other European countries. Several sorts of copal are known in British trade, as Brazilian, Indian, African, etc., the produce of different plants, but as an illustration of the difficulty of solving the question accurately, as to the names of these plants, we may mention that what is known in commerce as Bombay anime, is not an East Indian product at all, but is sent to Bombay from the East African coast, and then re-shipped to England, so that the commercial name in this instance as in many others is no guide, but rather leads us astray in reckoning upon the geographical position of the plant. Dammar, or East Indian copal, is said to be the produce of Vateria indica; piney resin, of which very little we believe is now imported, is said also to be produced from the same

tree. Yet piney resin is very different in appearance to what is commercially known as Indian copal, it is nevertheless a good clear resin, and gives off while burning an agreeable fragrance, so that the natives on the Malabar coast make candles of it; ornaments, such as beads, etc., are also made from it, and they much resemble amber. Much of the dammar, as seen in our markets, is, no doubt, the produce of Dammara orientalis, a large coniferous tree, growing in the Moluccas. Dammara Australis, a New Zealand tree, furnishes Kawrie resin, sometimes known as Australian dammar, and Australian copal; it is dug up from a depth of two or three feet below the surface of the ground. The natives are very quick in discovering it, probing the ground with long iron spikes, and sometimes alighting upon extensive beds. The resin is dug up in very large masses or blocks, sometimes as large as a man's head.

In India many kinds of dammar are known, as for instance, black dammar, said to be produced from Canarium strictum, Saul dammar from Shorea robusta, and so on, the botanical sources of many of which are unknown. What is known in commerce as Brazilian copal is probably produced by species of Hymenæa.

Dr. Daniell, who resided some time in West Africa, and who published a paper on copal in the "Pharmaceutical Journal," in 1857, classes the commercial sorts into three distinct kinds-East Indian, American, and African. As regards the former, it has since been proved as we have before said, to be sent originally from Eastern Africa to Bombay, and re-shipped from thence to Europe. But the true Indian copal or minul, and which is sometimes called piney resin, is doubtless furnished by Vateria Indica. The American, Dr. Daniell divided into two sections, Mexican or Brazilian, or North and South American. Amongst the plants yielding this description of copal, were enumerated, Icica, Elaphrium copalliferum, Dl., and E. excelsum H.B.K., Rhus copallinum, L., Trachylobium Martianum, Hayne, and other species of Trachylobium. Whether or not, commerce is indebted to all these plants to increase the bulk of that resin, so valuable in this country, we are not prepared to endorse; but considering that the Hymenea courbaril, L., is a well-known, indeed a common tree, in the West Indies, Brazil, Guiana, and in short, in most parts of tropical South America, and knowing that from this tree exudes large quantities of a clear copal-like resin, it is not unreasonable to suppose that it may be one of the trees from which our supplies of copal are obtained. Masses of this resin from the Hymenæa, were exhibited in the British Guiana collections of the International Exhibition of 1862, and in Paris in 1867. The trees

which are known in British Guiana as Simiri or Locust, grow in the forests of that colony to a great height, often reaching sixty or eighty feet before a branch is given off. The lower part of these gigantic trunks are supported by huge buttresses, a representation of which is given by Martius, and copied at p. 551 of Lindley's "Vegetable Kingdom." Even above these buttresses, where the trunk is cylindrical, they have been found to measure as much as sixty feet in circumference, and as regards their ages, it has been computed they must have been large trees at the commencement of the Christian era. The wood is exceedingly hard and dense, and a good deal of it is brought into this country for use as treenails in planking vessels, as well as for beams and planks for heavy engine work. The gum or resin, which in the colony is called gum anime, and which is of a very clear yellow colour, is said to be found only by digging near the roots of the trees. Some specimens which were shown in the International Exhibition, 1862, and which are now in the museum at Kew, have not the slightest trace of the fretted surface known as "goose-skin," which is found on the best African copal, though the large masses or blocks have somewhat the appearance of a stalagmitic formation, and a peculiar worn or dirty appearance where it has not been made bright by recent fracture. Air bubbles, channels in which pieces of stick have been imbedded, insects, and such characteristics common to copal also occur in this resin. Though digging near the roots of the trees is said to be the usual way of obtaining it, it will nevertheless flow freely upon tapping the tree, the juice exuding and hardening on the trunk, large solid masses are quickly formed. That the trees are highly charged with resin can be easily seen from the fruits themselves, the large woody pods when dry are covered with little warts or irregularities, which upon scratching will be found to be mere resinous secretions, simply covered with a thin epidermis. The fruits of Trachylobium Mossambicense are much more highly charged with resin, for while the fruits themselves are not more than a tenth the size of those of H. courbaril, the tubercles are considerably larger, and consequently contain much more resin; further than this, the pods are not so ligneous, so that the resin is more diffused amongst the tissues, this resin is of a very light colour and transparent, and burns freely with a clear flame. Fine specimens of the bark of this tree (Trachylobium Mossambicense, Kl.) with the resin in situ are in the museum at Kew, and were received from Lieut.-Col. Playfair, during the period of his residence as Consul at Zanzibar. The resin as seen in these specimens is of a dusky exterior, but bright clear yellow fracture, scarcely so light in