278 Dr. A. B. Macallum. On the Demonstration 



supposed connexion with haematopoiesis in the developing chick, he 

 named hsematogen. In the amphibian ova also the iron is united 

 with a proteid fixed in the yolk spherules, and as this proteid has 

 all the characters of a nuclein, it is, therefore, in all probability, the 

 same compound as that described by Bunge. This nuclein is, appa- 

 rently, none other than the chromatin diffused from the nucleus of 

 the maturing ovum. If so, it is possible that the original unmodified 

 nuclear chromatin of the ovum contains iron. Again, the fact, that 

 the lower Vertebrata receive the iron which is present in them during 

 larval life in combination with a nuclein, points to the occurrence 

 during the embryonic period in Mammalia of the same or a similar 

 endowment with an iron-holding nuclein. There is, in the Cat, as 

 stated already, a transference of chromatin from the maternal to the 

 fo3tal tissues. Judging from all the aspects of these questions it was 

 inferred also that, in the transference of chromatin to the embryo, 

 the latter receives all the iron which it requires. 



These points, taken in connexion with the fact that Zaleski isolated 

 from the liver cells of various animals a nuclein in which iron is 

 firmly bound, led me to the generalisation that the chromatin of 

 every cell contains iron as a necessary constituent of itself. I deter- 

 mined to test the accuracy of this generalisation. Under iny direc- 

 tions, Mr. B. R. Bensley isolated, from lamb's testicles and the calf's 

 thymus, quantities of nuclein, which, when carefully purified, gave 

 not the slightest iron reaction, but in the ash of which there was 

 abundant evidence of the presence of the metal.* 



Although care was taken to obtain the nuclein free from 

 heematin, yet I was not certain that we did obtain it absolutely in a 

 pure condition. It is well known that fixed or dead chromatin 

 readily absorbs dyes, and, as it is extremely probable that this power 

 is exercised on other substances, it may well be believed that 



* In the preparation of nuclein from these sources we proceeded as follows : 

 The organs, freed from connective tissue structures, were finely minced and rubbed 

 up in a glass mortar with a small quantity of a 2 per cent, solution of hydrochloric 

 acid. To this fluid, after having been strained through moderately fine muslin, 

 to remove small portions of fibrous tissue, more of the weak solution of the acid 

 was added, with a small quantity of a glycerine extract of the mucosa of the cardiac 

 portion of the pig's stomach. The fluid so prepared was kept at a temperature of 

 35 C. To the undigested residue left each day fresh quantities of the hydrochloric 

 acid solution and of the glycerine extract were added, until the peptone reaction 

 was no longer obtainable from it. It was next washed with alcohol, then carefully 

 with ether, to remove all the fat, and submitted to the action of strong ammonia 

 for twenty-four hours. A portion was thus dissolved, and the solution, freed from 

 the insoluble part by filtration through iron-free paper, was next treated with three 

 times its volume of alcohol. The precipitate from this was removed, again dis- 

 solved in ammonia, and reprecipitated with alcohol. The nuclein so obtained gave 

 no iron to Bunge's fluid, nor did it give to alcohol acidified with sulphuric acid any 

 hae matin. 



