the requirements of this volume are concerned. The edge should be kept permanently sharp. Before cutting, pare away the imbedding material, so as to reduce that which surrounds the preparation to the minimum. 3. Mounting. a. b. Transfer the sections as cut, paraffin and all, to microscopic slides previously prepared by one of the two undermentioned methods, and proceed as directed in either case. White of egg method. Smear the surface of the slide with a thin but uniform film of freshly drawn white of egg and deposit the sections in order of cutting. Gently heat the slide until the paraffin begins to melt and then put it aside. When set, put the whole bodily into turpentine and leave it until all the paraffin is dissolved out; upon examination the sections will be found to be firmly attached to the glass slide by means of the coagulated albumen. Immersion in turpentine for an indefinite period will do no harm. Kreasote and shellac method. Smear the surface of the slide with a heated solution of white shellac in Kreasote. Submit the whole to the temperature of the melting point of the paraffin until the kreasote is evaporated, whereupon the sections will become firmly adherent to the glass by means of the shellac. Next immerse the whole in turpentine, and leave it at rest until the excess of imbedding material is dissolved out. This method is best applicable to preparations which have been previously stained and clarified. The white of egg process is not only the simpler of the two, but the more advantageous, as the sections may be cut and mounted unstained, that process and the subsequent clarifying being permissible after fixture to the slide. 4. Final mounting. 5. 6. Allow sufficient of the canada balsam to drop upon the sections to fully cover them. When thoroughly diffused among them, smear the under face of a cover-slip with balsam and place one edge of it upon the slide supporting its body upon the point of a needle; by gradually withdrawing the latter the cover-slip will descend obliquely expelling the enclosed air. Finished preparations should be examined from time to time, in order that loss of the mounting medium by evaporation may be made good. To prepare ground sections of shells, bones, or other hard parts. A small piece of the structure to be manipulated should be first isolated and then cemented in the desired position to a piece of plate glass, by means of canada balsam. When firmly set it should be ground down upon a hone or rough surface to the required thinness, and finally dislodged for mounting, by immersing the whole in benzole or chloroform. It may then be put up in canada balsam in the manner described above. Frozen sections. Material for this purpose should be preserved in weak glycerine. For the preparation of these sections an etherspray freezing microtome is desirable; good preparations may however be made as follows. Obtain a metal rod of the calibre of a candle and 2—3 inches in length: place the preparation (which, unless quite fresh, should be previously soaked in gum-water) on one end of it and add 6-8 times its bulk in ordinary fluid gum. Freeze with pounded ice and salt. Cut. Mount in weak glycerine. INDEX. A. ABDOMEN, 174, 190, 192, 238 Adipose tissue, histology of, 131 Adventitious buds, 444. Albumen gland, 289; duct of, 290 Alga, 392, 396, 436 Alimentary canal, Crayfish, 178, Ambulatory appendages, 175, 197 Amoeboid movement, 123 Anacharis, 442 Angulo-splenial, 62 Annulus, Fern, 449, 457; tym- Anodonta cygnea, 305-341 Antennule, 176, 201 Antheridium, Chara, 431, 433, Antherozoid (see Spermatozoid) Aorta, Frog, 19, 20, 86; Snail, Appendages, Chara, 430; Cray- Aqueduct of Sylvius (see Iter) Archegonium, 450, 459, 466 Cellulose, 379 Cement glands, 186, 235 Cephalothorax, 173, 190, 193, 237 467; Chara, 433; Fern, 447; Hy. Chloroplastid, Hydra, 356 (see 391, 393; Spirogyra, 397, 404 Ciliary action, Frog, 124; Vorti- Ciliated groove, 322, 338 19, 92 Circulatory system, Crayfish, 180, Circulus venosus pulmonis, 295 Clitellum, 245, 248 Cloaca, Frog, 2, 10, 47; orifice of Cnidoblast, 346, 355 Cocoon, 247 Cochlea, 33 Collateral bundle, 463 COLOURLESS BLOOD CORpuscle, Columella, Mucor, 421; Snail, Concentric bundle, 446 Conjugation, Amoeba, 373; Mu- Conjunctiva, 44 Connective rod, 185, 234 Connective tissue, histology of, Coracoid, 69 |