ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 303 



to settle for ten minutes, then draw off tlie water with the siphon and 

 repeat the process until perfectly clear. 



Next attack the fine sand. Take a shallow glass dish with very 

 slightly concave bottom (a photographer's " bender " is most suitable), 

 and place in it a quantity of the material not sufficiently great to heap 

 up much. Separation is effected by rocking and tipping and shaking 

 gently from side to side. As the diatoms are separated from the sand, 

 draw them off with a pipette, add more water, and continue until none 

 are left ; repeat the process until all the sand is removed. Next allow 

 to settle until all forms desired in a given settling are precipitated, 

 draw off the water into a larger vessel, fill up the vial, shake and settle 

 the same length of time as before, and continue until everything which 

 will not settle in that time is washed out. The material will then be 

 finished. Then take the residue, shake and settle longer, to deposit the 

 next smaller forms desired. Proceed thus until all the forms are 

 separated. If it be not desired to separate the different forms, but only 

 to remove any fine particles which may remain, simply shake the vial 

 vigorously, allow the material to settle until the Microscope shows that 

 all the diatoms have sunk, siphon off the water and renew it, adding a 

 few drops of ammonia, and repeat until all is clear, always replacing 

 the filtered with distilled water in the last three or four shakings. As a 

 mounting medium the author considers that styrax properly prepared is 

 superior to any other and that no cement is better than hard oil finish. 

 This, with the addition of finest dry lampblack, makes a cement that is 

 not excelled. 



Chitin Solvents.* — Mr. T. H. Morgan uses the Labaraque and 

 Javelle solutions (potassium and sodium hypochlorites) for dissolving 

 the chitinous parts of insects, so that they may be sectioned and rendered 

 penetrable to staining fluids. The material, say the eggs of the common 

 cockroach surrounded by the chitinous raft, is placed in the Labaraque 

 solution, diluted five or six times, and slightly warmed for thirty minutes 

 to an hour. The embryos are, after being well washed, then trans- 

 ferred to picrosulphuric acid, then to alcohols up to 95 per cent., then 

 imbedded in paraffin cemented on the slide, and stained on the slide. 



Corrosive sublimate and chromic acid were also used, but with less 

 satisfactory results. Embryos transferred directly from Javelle solution 

 to alcohol were nearly as good as those put through picrosulphuric acid. 



B E N D A, C. — Makroskopisclie und mikroskopische Praparate fiir eine neue 

 Hartungsmethode. (Macroscopical and microscopical preparations for a new 

 hardening process.) 



Anat. Anzeig., III. (1888) p. 706. 

 (^Ver/i. Anat. Oescllsch. Wm-zlnir;).) 

 Geeppin, L. — Mittheilungen iiber einige der neueren Untersuchungsmetlioden 

 des Centralen Nervensystems. (Notes on some of the recent methods of investi- 

 gating the central nervous system.) 



Corrbl. Schweizer Aerzte, XVIII. (1888) No. 16. 



M s s 0, A. — Esame critico dei metodi adoperati per studiare i corpuscoli del sangue. 



(Critical investigation of the metliods used in the study of the blood-corpuscles.) 



Atti R. Accad. Lincei—Rend., IV. (1888) pp. 427-33. 



„ „ Kritische IJntersuchung der beim Studium der Blutkdrperclien 



befolgten Methoden. (Critical investigation of the methods used in the study of 



the blood-corpuscles.) 



Virchow's Archiv, CXIII. (1888) p. 410. 



Amer. Mon. Micr. Journ., ix. (1888) p. 234. 



