516 SUMMARY OF CURRENT RESEARCHES RELATING TO 



obtained. Staining may also bo effected on the slide if a nerve-end 

 apparatus be spread out and a dilute solution of metbyl-blue be added. 

 Staining the retina of fish, birds, and mammals is moro successful by 

 this method than by injection. In other parts this method gave less 

 favourable results. 



Demonstrating Karyokinetic Figures.* — Dr. G. Martinotti and 

 Dr. L. Eescgotti proceed as follows to demonstrate karyokinetic figures. 



The tissues are fixed with absolute alcohol. The sections are stained 

 by leaving them five minutes in an aqueous solution of safranin and 

 the stain is differentiated by transfering them to a spirit and water 

 solution of chromic acid. This solution is prepared by mixing one part 

 (by volume) of a watery solution of chromic acid (1:1000) with nine 

 parts of absolute alcohol. In this very dilute solution the sections are 

 left for a half or one minute, agitated therein, and then dehydrated in 

 absolute alcohol, cleared up in bergamot oil, and mounted in dammar. 

 In this way the chromatin filaments and the true nucleoli are stained a 

 lively red, the protoplasm and the intercellular substance remain un- 

 coloured, the resting nuclei are faiutly stained a pale red. 



The spirit and water solution of chromic acid should be prepared 

 fresh every time. In some cases it is useful to employ a slightly 

 stronger solution, that is, to mix two volumes of the watery solution of 

 chromic acid (1:1000) with eight parts of absolute alcohol. At other 

 times it is advantageous to dilute the watery solution of safranin with 

 an equal volume of distilled water, and to leave the sections therein for 

 five minutes, then keep them in the chromic acid solution until they have 

 assumed a uniform rose tint. 



The authors in conclusion remark that safranin seems to have a special 

 affinity for the chromatin of the nucleus, that they have been unable to 

 convince themselves that anilin oil is detrimental to nuclei in motion, and 

 that oil of cloves, as previously noted by Bizzozero, extracts the anilin 

 dyes more quickly from nuclei in repose than from those in mitosis. 



Staining Membranes in Living Siphoneae.f — Dr. F. Noll finds that 

 in Caulerpa prolifera, some kinds of Bryopsis and Derbesia, and some 

 Floridese, the membranes become thickened by deposition of new layers. 

 If the original membrane be stained without damaging the plant, it is 

 seen that on further growth new unstained lamella? are deposited upon 

 the stained parts. The author coloured the membrane with Berlin or 

 Turnbull's blue in the following way : — One part of sea water was 

 diluted with two parts of sweet water, and in the mixture so much 

 ferrocyanide of potash was dissolved as to give it the specific gravity of 

 sea water. A second fluid consisted of two parts sea water and one 

 part sweet water, and some drops of chloride of iron. This solution 

 must be made fresh before each time of using. If Turnbull's blue were 

 used the solutions were ferrocyanide of potash and lactate of iron. The 

 deposition of Berlin blue was effected by removing the plants from 

 sea water to the cyanide solution (1-3 seconds) ; they were then washed 

 in sea water, and immersed for 1/2-2 seconds in the iron solution. The 

 plants were next again removed for a moment to the ferrocyanide 

 solution, and afterwards washed in much sea water. Care was always 

 taken that the cyanide should be in excess in order that the iron chloride 

 should never come in contact with the plasma as iron chloride. By 



* ZeiUchr. f. Wiss. Mikr., iv. (1887) pp. 326-9. 

 t Bot. Ztg., xlv. (1887) pp. 473-82. 



