474 SUMMARY OF CURRENT RESEARCHES RELATING TO 



objects were then hardened in 96 p.c. and in absolute alcohol, and after- 

 wards passed through xylol to paraffin. For young larvae \ to 1 hour 

 in melted paraffin was sufficient ; the larger ones on account of the fat 

 bodies required several hours. 



Longitudinal and transverse sections were made, the former being 

 both sagittal and frontal. In thickness the sections varied from 2| to 

 15 n, according to the size and the cuticular density of the animal. 

 The sections were stuck on with glycerin albumen, but occasionally with 

 water; they were then stained and imbedded in balsam. The stain 

 mostly used was Bohmer's hematoxylin followed by picrocarmin, but 

 other pigments were also tried. 



Preparing and Demonstrating the Structure of Arenicola.* — 

 J. H. Ashworth adopts the following procedure for making sections of 

 Arenicola (lugworm). It is advisable to use specimens not longer than 

 (5 in., as longer ones are difficult to deal with on account of the hardness 

 of the musculature. The sand is first removed from the alimentary 

 tanal by keeping the animals for 4 or 5 days in sea water. When free 

 from sand, absolute alcohol is dropped in until the water contains about 

 5 p.c. After a few hours the animals will be sufficiently narcotised and 

 may then be killed in the extended condition by treating them with 

 sublimate acetic (95 parts sublimate and 5 parts glacial acetic acid) for 

 a few hours. On removal, the worms are washed in fresh water and 

 then transferred to alcohols of increasing strength (50, 70, 90). To 

 the last, iodine is added to remove the subJimate. Pieces intended for 

 sectioning are then dehydrated in absolute alcohol (three changes) and 

 then cleared up with xylol or, preferably, cedarwood oil. The pieces 

 are next impregnated with paraffin in the usual way. Wax with a 

 melting-point of 56° to 58° C. is best for Arenicola. 



The best staining results were obtained with iron-alum-haematoxylin, 

 but borax carmin, acid basmalum, Grenadier's and Delafield's hema- 

 toxylin were also used. 



Modification of Zenker's Fluid.f — K. Helly recommends the fol- 

 lowing modification of Zenker's fixative : it consists of potassium bi- 

 chromate 2*5, sulphate of soda 1, sublimate 5, distilled water 100. 

 To 100 parts of this fluid are added, immediately before use, 5 parts 

 of formalin. This solution works better at incubation temperature, 

 and should not be allowed to act for more than 6 hours. The after 

 treatment is the same as for Zenker's fluid, viz. thorough washing, 

 graded alcohols, and iodine alcohol to remove sublimate. 



Dowdy, S. E.— Preparing Diatoms. English Mechanic, Ixxix. (1904) p. 194. 



Smith, H. E.— Ditto. Loc. cit. 



(3) Cutting, including Imbedding and Microtomes. 



Preparation of Frozen Sections by Means of Anaesthol4 — Katz 

 advocates for the above purpose the use of anaesthol, a solution of 



* Liverpool M.B.C. Memoirs, xi. (1904) 118 pp., 8 pie. 

 t Zeitschr. wiss. Mikr., xx. (1904) pp. 413-5. 



t Deutsche Med. Wochenschr. (1903) No. 24. p. 331. See also CentralR Batt. 

 sxxiv. (1904) Ref. pp. 652-3. 



