978 SUMMARY OP CUREENT RESEA.ECHES RELATING TO 



Preparing Embryos.* — J. A. Eyder points out that in woiking 

 with vertebrate materials, hardening and killing should be done in 

 such a way as not to distort the axis of the embryos, in order that the 

 knife may be adjusted so as to cut in any desired plane with accuracy. 

 The imbedding must be as homogeneous as possible ; for this pur- 

 pose saturating the object with paraffin has been found to be the best, 

 so that evenly thin sections may be produced. The methods of 

 Biitschli, Plateau, Calberla, Duval, all serve this purpose, and 

 their relative values are probably expressed in about the order in 

 which they stand. Staining is best accomplished by dyeing the 

 object as a whole ; mounting should be done serially and with the 

 ribbon method. 



Method of Studying the Amphibian Brain.f— Prof. H. F. Osborn 

 hardens the brain in Miiller's fluid (bichromate of potash), the ven- 

 tricles being fully injected. After the usual alcoholic treatment, the 

 brain is placed for one week in a carmine solution, then for twenty-four 

 hours in acetic acid. 



The imbedding mass is prepared by shaking the contents of an 

 egg with three drops of glycerin. After soaking in this mass, the 

 brain is placed in position, and hardened in the vapour of boiling 

 80 per cent, alcohol. The mass is then placed for one week in absolute 

 alcohol. 



Sections are made under alcohol with a Jung's microtome, fifty or 

 sixty sections collecting on the razor in alcohol are then floated at 

 once, in order, upon the slide. To keep them in place, they are 

 covered with old-fashioned blotting-paper (cigarette-paper was sug- 

 gested as better by Dr. C. S. Minot) and treated with alcohol and oil 

 of cloves through the papers, a device which may prove convenient in 

 many cases. 



Preparing Planarians and their Eggs.J — In the preparation of 

 Planarians for histological study, J. Jijima recommends corrosive 

 sublimate as the only good preservative agent. The worms are 

 placed in a shallow plate, without water, and a saturated solution of 

 corrosive sublimate, heated almost to boiling, is poured over them. 

 In this way they are killed so quickly that they do not have time to 

 contract. They are left thirty minutes or less in the sublimate, then 

 placed in water for an hour or more. The water should be changed 

 several times, in order to remove all the sublimate; otherwise it 

 forms needle-like crystals, which impair or ruin the preparation. 

 Three grades of alcohol (" weak, strong, and absolute ") are used in 

 hardening, in each of which the object should be left at least forty- 

 eight hours before staining. Borax-carmine (probably the alcoholic 

 solution) is recommended as a staining agent ; a dilute solution is 

 used in preference to the full strength, and allowed to act from three 



* Amer. Mon. Micr. Journ., v. (1884) pp. 190-1. 



t Science, iv. (1884) p. 343. Abstract of paper read before the Philadelphia 

 Meeting of the Amer. Assoc. Adv. Sci. Also Amer. Mon. Micr. Jonrn., v. (1884) 

 p. 188. 



X Zeitschr. f. Wiss. Zoo!., xl. (1884) pp. 359-464 (4 pis.). Amer.. Natural., 

 xviii. (1884) pp. 1068-9. 



