780 REPORT— 1892. 



have observed that the silk of certain insects (chironomus, for instance) seems to 

 possess a stronger affinity for this metal than nuclein itself. 



To sum up briefly the present state of the question, it is now certain that 

 dead nuclein, as well as other substances found in the cell, have a very strong 

 affinity for various compounds of iron and of other metals, or even negative 

 chemical bodies. Thus the difficult question arises, whether the presence of iron 

 in the nucleinic element during life is constant and normal, and whether this 

 metal is necessary for the chemical activity of the nucleus. 



I hope these remarks will induce other biologists to undertake similar researches 

 on a question that seems to require more than a single man's activity ; and that 

 is the reason why I resolved to pubUsh my results in their present incompleta 

 form. 



8. A Method of Staining Gliromatin hy Chemical Means. 

 By Professor G. Gilson, oJ Louvain. 



The fact that metallic compounds are easily fixed in nuclein suggested to me a 

 pecidiar method of staining nuclei that, perhaps, might be of some use for special 

 histological and cytological researches. It consists either in keeping cells, pi'e- 

 viously hardened, in the metallic solution during a certain time, or in adding this 

 latter directly to the usual fixing liquids. Then, after the solution has been 

 thoroughly washed out, the objects are put into ammonium sulphide or potassium 

 ferricyanide, or into both, and washed again. 



I succeeded by this method in staining the chromatic elements of many 

 animal and vegetable cells, after the action of picro-sulphuric acid, Perenyi's fluid, 

 corrosive sublimate, especiallj^ the acid solution used in my laboratory, and others. 

 But I did not succeed up to the present, after using Flemming's fluid or other 

 chromic liquids. 



The colouration is always characteristic, provided the object has been suffi- 

 ciently washed before the reagent is applied. 



I am still studying the best method to get a good dark colouration. Satis- 

 factory results, however, have been obtained with the following solution, as well 

 for fixing and hardening the cell as for staining the nuclei : — 



c.c. 

 Iron sulphate, 10 per cent. aq. . . . .10 



Nitrate of nickel, 50 per cent, aq 10 



Alcohol, 90 per cent., or, better, aldehyde saturated 

 with sulphurous anhydride . . . . .10 



Sulphuric acid 2 



Alcohol, 90 per cent 40 



7a 



After some hours' steeping in this fluid, objects are washed with weak alcohol, 

 then with water, and put into ammonium sulphide for a few minutes. Alter 

 another washing with alcohol and with water they are steeped for about half an 

 hour in a weak solution of potassic ferricyanide acidulated with hydrochloric acid 

 and washed again. 



Each of the substances composing the solution, except alcohol, has the effect 

 of making nuclei colourable with ammonium sulphide or with potassium ferri- 

 cyanide ; but I noticed that better results are obtained when they are mixed 

 together in the above-mentioned proportions. 



The action of potassium ferricyanide is much quicker and more intense when it 

 succeeds that of ammonium sulphide. This latter does not harm in the slightest 

 way the cells previously treated with the mixed solution or with the usual fixing 

 liquids, though it seems better, at all events, not to use it too concentrated. 



9. A pro]posed Reform in Botanical Nomenclature, 

 By James Beitten. 



