ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



249 



(2) Preparing- Objects. 



Improved Method of Dehydration.* — B. Suzuki considers that the 

 ordinary method of dehydration, by which objects are placed successively 

 in 50, 70, and 00 p.c. alcohols, is unsuitable for delicate objects, and 

 describes an apparatus (fig. 36) by which the concentration of alcohol 

 is increased gradually. G x and G 2 are filled with distilled water ; the 

 inverted flask K is filled with 50 p.c. alcohol. The material M is placed 

 in G 2 , resting on washed sand S. The junction tube W is filled with 

 glass-wool. As water trickles away through the capillary tube A, an 

 alteration of level in G x causes 

 alcohol to enter slowly from the 

 inverted flask, and so the concentra- 

 tion process proceeds automatically. 

 It is only necessary to re-fill the 

 flask, when it become empty, first 

 with 70 p c, then with 90 p.c, and 

 finally with absolute alcohol. The 

 same apparatus, with slight modifi- 

 cations, may be used for hardening 

 and washing processes. 



New Methods of Investigating 

 the Central Nervous Systems of 

 Vertebrates.f— Under this title B. 

 Rawitz describes new methods of 

 fixing and staining portions of brain 

 and spinal cord. Material, which 

 has been preserved in 10 p.c. forma- 

 lin, is transferred to a 10 p.c. solu- 

 tion of tincture of iodine in 95 p.c. 

 alcohol. After 5 days the material 

 is removed to a saturated watery 

 solution of potassium bichromate. 

 This solution is changed after 24 

 hours, and in this second bichromate 

 bath the tissues remain for 7 to 10 

 days, according to the size of the 

 pieces. They are then removed, dried with filter paper, and put into 

 95 p.c. alcohol for 3 days, absolute alcohol for 2 days, and chloroform 

 for 2 days. Then after 24 hours in chloroform-paraffin, the material is 

 imbedded in paraffin. 



The author gives accounts of a number of new stains, namely indulin, 

 indamin-blue, and azo-acid-blue. The last-named stain, made up in the 

 following combination — azo acid-blue B (Hochst), 2 grm. ; tartar emetic, 

 1 grm. ; oxalic acid, 4 grm. ; distilled water, 200 c.cm. — gave good results. 

 The ganglion-cells and neuroglia are coloured purple, the axis-cylinders 

 light blue. With this stain made up in some other combinations, the 

 author could not obtain this amphichromatic effect. He ends his paper 

 with illustrations of the application of his methods. 



* Zeitschr. wiss. Mikrosk., xxvi. (1909) pp. 211-19. 

 t Tom. cit., pp. 337-52. 



April 20th, 1909 S 



Fig. 36. 



