1891.] 



Presents. 



489 



vegetable. The ordinary method of isolating chromatin employed 

 in chemical and physiological laboratories cannot be readily applied 

 in testing the correctness of this supposition. It is conceivable that 

 this substance absorbs and retains tenaciously iron-holding com- 

 pounds as readily as it does some of the dyes used by the histologist. 

 It is not easy to remove such compounds without, possibly, decompos- 

 ing the chromatin, and, when the latter is prepared in any quantity, 

 one cannot be certain that the iron which is present may not be an 

 impurity. To overcome this difficulty, one must prepare chromatin 

 from organs which are free from haematin or like substances, or 

 from inorganic iron compounds, and, for this purpose, fairly large 

 quantities would be necessary for chemical manipulation. There is. 

 apparently, no organ, animal or vegetable, which offers such an 

 opportunity. There consequently remains but one other way by 

 which the view, that iron is constantly present in chromatin, can bt! 

 put to the proof, and that is the micro-chemical one. I have found 

 that a certain metbod of employing ammonium sulphide as a reagent 

 for iron shows the presence of the latter in the chromatin of the 

 nuclei of a very large number of species of cells hardened in alcohol. 

 The iron in this case does not occur combined as an albuminate, but 

 rather in a condition which, as regards the firmness of the combina- 

 tion, is comparable to that present in potassium ferrocyanide or 

 hsematin. That the iron found is not due to the presence of haematin 

 is shown by the results of experiments made with vegetable cells, and 

 with animal cells which one would not naturally expect to contain 

 hsematin, as, for example, those of the corneal epithelium in Amphibia. 

 In support of this may also be mentioned the fact that where chro- 

 matin is very abundant the iron reaction is very marked, while it is 

 feeble in cells poor in chromatin. In the chromatin loops and 

 filaments of karyokinetic figures the iron reaction is intense and 

 sharply confined to these structures. 



I forego, for the present, any expression of opinion as to the general 

 application of the results obtained. I would not even maintain that 

 the chromatin of every cell essentially contains iron, although my 

 studies have, so far, not furnished an instance which can support the 

 contrary view. 



The Society adjourned over Ascension Day to Thursday, May 14. 



Presents, April 30, 1891. 

 Transactions. 



Adelaide : Royal Society of South Australia. Transactions. 

 Vol. XIII. Part 2. 8vo. Adelaide 1890. The Society. 



Berlin : Gesellschaft fur Erdkunde. Verhandlungen. Bd. XVII I. 

 No. 7. 8vo. Berlin 1891. The Society. 



