190 T. E. WALLIS : THE STRUCTURE OF PEPPER: SOME NEW FEATURES. BY T. E. WALLIS. (Read at the Meeting, March 3, 1915.) DURING the microscopical examination of the crude fibre from some trade samples of white pepper, I noticed several pieces of tissue showing strongly marked characters which are not included among those described and figured in the available textbooks and atlases. This led one to suppose that the samples might contain some added material other than pepper.Having noted that all the specimens examined con- 1 2 3 4 FIG. I.-BEERIES OF WHITE PEPPER ( x 7). 1, Berry seen from the side, showing depression above and conical projection below. 2, Base of berry, showing conical projection. 3, Base of berry, showing pigment layer exposed by removal of the parenchyma forming the cone-shaped projection.4, Apex of berry, showing depression. tained these tissues, it seemed possible that they were actually structures properly belonging to pepper, but which had been overlooked and omitted from the published descriptions. An examination of the crude fibre prepared from a sample of pepper obtained by powdering white pepper berries revealed the presence in authentic material of the same tissues, and so demonstrated the genuineness of the original samples.Some white pepper berries (Piper nigrum, L.) were next examined, with a view to finding portions which might be expected to show structures of a special type, and it was then noticed that peculiarities might be sought at the apex and a tTHE STRUCTURE OF PEPPER: SOME NEW FEATURES 191 the base of the fruit, which are marked respectively by a slight circular depression and a small bluntly conical projection (Fig.I., 1, 2, and 4). In many berries the parenchyma forming the conical part is rubbed off, and a brown circular patch-the pigment layer-becomes exposed, as shown in Fig. I,, 3. Scale 4J microns. 1 ' * _ - * ' * - - ' * ' s f 0 50 I00 150 FIG.II.-PREPARATIONS FROM THE APEX OF THE WHITE PEPPEK BERRY. 1, Diagram showing general disposition of the tissues present ( x 18). 2, Transverse section of the seed coats and inner portion of the pericarp from just above the embryo ( x 400). 3, Surface view of the tissues shown in the transverse section. a, Innermost layer of the pericarp. e, Embryo. end, Endo- sperm. hy, The hyaline layer.par, Parenchyma. per, Perisperm. pig, Pigment layer. scE, Inner sclerenchyma of the pericarp ( x 400). The diameter of a white pepper berry is about 4 mm., giving an area of about 50 sq. mm. ; the diameter of the slightly conical area at the base is about 2 mm. and of the depression over the embryo at the apex is 0.75 to 1.0 mm., giving areas192 T. E. WALLIS: of 3.1 and 0.8 sq.mm. respectively, so that the total area of these two regions is about one-twelfth of the whole area of the fruit, and the tissues of which they are composed must form a considerable part of the fibre obtained from samples of white pepper. Berries were soaked in water until sufficiently softened and the apex and Scale of mic~ons. 0 60 I00 160 FIG. I I I . 1, Transverse section of seed coats and inner part of the pericarp from the equator of the fruit.2, Surface view of the same tissues. a, Innermost layer of the pericarp. hy, Hyaline layer. o.g, Oil gland. par, Parenchyma. per, Perisperm. pig, Pigment layer. scE, Inner sclerenchpa of the pericarp. All x 400. base cut off. The sections which were made of these portions revealed modifications such as were being sought.In a, transverse eection of the apex of the berry the hemispherical hollow, containing the endosperm, appears as a, semicircular area just below the pigment Iayer, and the embryo itself occupies a similar smaller area in the upper part ofTHE STRUCTURE OF PEPPER: SOME NEW FEATURES 193 the endosperm. The general arrangement of the tissues is shown disgrammatically in Fig.II., 1. The inner sclerenchyma of the pericarp is more lightly built in this region than in other parts of the fruit, as may be seen by a comparison of Figs. 11. FIG. Iv. 1, Innermost layer of the pericarp from over the embryo ( x 106). 2, A portion of the same as found in powdered pepper, and more highly magnified ( x 200). 3, Hyaline layer, showing transition from straight-walled cells to those with wavy walls ( x 200).and 111. ; otherwise it is very similar. The narrow layer of the pericarp within the sclerenchyma appears in sections from the middle of the fruit as ti narrow, nearly194 T. E. WALLIS structureless band (Fig. III., 1, a), having a slight brown colour and showing in the form of short lines the compressed lumina of the cells of which it is composed.In surface view (Fig. II., 2, a) it is seen to consist of thin-walled, irregularly polygonal cells, measuring 15 to 40 p in either direction. In a section from the apex of the fruit the same layer appears as a single row of cells, with very thick sparsely pitted walls and rectangular lumina. They have a height of about 20 p and are from 15 to 40 p wide.In surface view the cells are seen to converge upon the centre of the small circular area covering the endosperm, their long axes being directed towards the centre (Fig. III., 2, a ; and Fig. IV., 2). Their length varies from 40 to 130 p ; the walls are thick and show pits, particularly in the angles. At the centre of this area is a small opening (Fig. IV., I), which marks the end of the canal through which the pollen-tube passes to the ovary.The pigment layer, which comes next, is also modified. Ordinarily it consists of flattened rectangular cells (40 to 80 p long and 12 to 18 p wide), filled with dark brown contents, as shown in Fig. III., 2, pig. At the apex of the fruit above the embryo, the cells, as seen in a vertical section of the fruit, gradually increase in height from 5 to 40 p and decrease in width from 50 to 10 or 20 p (see Figs.II., 2 ; and III., 1). In surface view the same cells are Been to be polygonal in shape and have thickened walls. They are from 10 to 25 p in either direction (Fig. II., 3, pig.). The hyaline layer shows a peculiar structure in this region. The cell walls, which in other parts of the fruit are straight (Fig.III., 2, hy.), are here thrown into folds, giving rise in transverse section to the appearance shown in Fig. II., 2, hy., and in surface view to a tissue consisting of cells with much waved walls and measuring from 30 to 50 p in either direction, as represented in Fig. II., 3, hy. The transition from straight-walled cells to those with wavy walls is shown in Fig.JV., 3. These three tissues are so strongly built and have such characteristic features that, although they only form a small proportion-about one-fiftieth-of the whole area, of their respective layers, they are found in every preparation of fibre from pepper, and unless known to belong properly to the fruit of Piper nagrum would lead one to the erroneous conclusion that some admixture was present. A section through the conical portion at the base of the fruit reveals the fact that the pigment layer is here again much altered, while the inner sclerenchyma of the pericarp, with the layer next to it, and also the hyaline layer outside the perisperm, disappear entirely (see Fig.V., 2). The formation of this prominence is due to the entrance of the fibro-vascular bundles into the pericarp at this point, whence they spread in all directions, to travel from the base to the apex of the fruit (Fig.I., 1 and 3), so that the parenchyma is specially supported in this region and is raised in the shape of a slight cone. The pigment layer increases in thickness from one cell to three or four, and finally to eight or ten cells, and continues at this thickness across the base of the conical prominence referred to above.Fig. V., 1, shows the general arrangement diagrammatically. The cells of the pigment layer are here less compressed and are of rather smaller dimensions, being 15 to 35 p in either direction, as seen in surface view. The superposition of several similar layers of cells produces a tissue of characteristic appearance when seen from aboveTHE STRUCTURE OF PEPPER: SOME NEW FEATURES 195 Scale C f r n t - C T O I L S . 1 * a; 1 ' * * I * J 0 so 100 CEO FIG.V. 1, Diagram of a transverse section through the conical projection a t the base of a white pepper berry ( x 27). 2, A ,ortion showing in detail the transition of the pigment layer from a narrow band to a wider one, and! the abrupt ending of the other tissues.3, Pigment layer in surface view. 4, Scler- enchymatous cells from periphery of the conical projection. a, Innermost layer of the pericarp. d, Pigment cells, showing delicate pitting of walls. f.v.b, Fibro-vascular bundle. hy, H aline layer. o.g, Oil gland. par, Parenchyma. per, Perisperm. pig, Pigment layer. sc2, Sclerenc&ma. sp, Spiral from a vessel.(2, 3, and 4 all x 400.)196 THE STRUCTURE OF PEPPER: SOME NEW FEATURES (Fig. V., 3). Some large sclerenchymatous cells are found on the outside of the conical projection of the base, and are shown in Fig. V., 4. Although no complete description of these tissues appears to have previously been given, reference is made to the occurrence of some of them in powdered pepper by Eugene Collin (Annales des FaZsiJications, 1910, 3, 272, et seq.).He says (p. 274) : ‘( Comme elements accessoires ou pourra retrouver dans quelques prises d’echantillon des cellules tr&s sinueuses, fortement colorees en brun, et d’autres aussi fortement colorees, assez regulihrement polygonales, ou cylindriques, qu’on serait tent6 d’attri- buer A la presence de matieres etrangeres ; il faut bien s’en garder ; car ces elements assez rares d’ailleurs sont normaux et representent des debris du tegument s6mina1, pris aux deux p6les opposes du fruit du poivre.” In the description attached to the figure of the anatomical elements of powdered pepper the cells having sinuous walls are erroneously referred to the base of the fruit, and are stated to be the modified pigment layer, whereas my preparations indicate that they belong to the hyaline layer, and come from the apex just over the embryo.The modified pigment layer from the base is also figured, but is stated in the description to come from the apex of the fruit. The pigment layer from the apex of the fruit, as seen in surface view, is also figured by M.Collin, and is correctly referred to the summit of the fruit. I have also been unable to confirm the presence of such numerous pits as to give a beaded appearance to the walls of the cells of the pigment layer covering the greater part of the fruit. In all preparations which I have examined they appear as shown in Fig. III., 2,pig. The cells from the portion o this tissue where it becomes several layers thick across the base of the conical end of the fruit do, however, show a delicate pitting which gives the walls a finely beaded appearance.Reference to modifications at the apex of the fruit is made by Tschirch and Oesterle in their (( Anatomischer Atlas der Pharmacognosie,” p. 105, where the appearance of the innermost layer of the pericarp and of the epidermis of the seed (the pigment layer), as seen in a transverse section, is noted, and a, drawing of s.uch a section is shown on Plate 25, Fig.13, of their Atlas. No description of these modified tissues in surface view is given, nor is their occurrence in powdered pepper referred to. DISCUSSION. Professor H. G, GREENISH said that he imagined that Mr. Wallis’s mode of procedure had been to concentrate the cellular elements in a comparatively small space, the starch being got rid of, while the delicate parenchymatous tissue of the perisperm became transparent and nearly invisible in chloral hydrate.Each particle would then have to be minutely examined in order to ascertain, if possible, from what part of the berry it came. He (the speaker) had carried out that very tedious process with 8ome other articles, and he sympathised with Mr.Wallis in his task. He should like to see some of the more common drugs taken in hand in the same way and examined as thoroughly. Mr. E. T. BREWIS asked whether there was any possibility that these new structures which Mr. Wallis had described might be confused with any part of the outer coats of black pepper.A METHOD FOR THE ESTIMATION OF CHLORIDES IN CHEESE 197 Mr.E. R. BOLTON said that extravagant claims were sometimes made as to the possibility of making quantitative estimations of the amounts of shell or husk by microscopical examination, and he thought it would be useful if Mr. Wallis would indicate what he considered to be the limitations of the microscope in this respect. Mr. WALLIS said that the tissues to which he had drawn special attention were so entirely different from those of the outer part of the pericarp that he did not think there was the least likelihood that any confusion would arise. The quantita- tive use of the microscope was a matter calling for very considerable caution. It was impossible to form any opinion as to quantity except by making up samples containing the genuine substances and the suspected admixtures in known pro- portions, and then, by microscopical comparison, getting an idea as to whether the foreign particles were present to a similar extent in the samples of known composition and in the suspected sample. This, of course, was necessarily very tedious, and in the end the results obtained were only roughly approximate.