SCIENCE- GOSSIP. 



369 



CHEMISTRY 



CONDUCTED BY C. AINSWOKTH MITCHELL, 

 B.A.OXON., P.I.C., F.C.S. 



Side-Chain Theory of Immunity. — It has 

 been demonstrated in various researches that when 

 bacteria or the toxines which they produce are 

 introduced into the living body of an animal 

 specific antagonistic substances are formed, which 

 afford protection against the same poison when 

 transferred to another animal. To account for 

 this phenomenon Ehrlich has proposed what is 

 known as the side-chain theory. He assumes that 

 a toxine molecule has two components, one of which, 

 the " haptophore " group, is unsaturated and stable, 

 whilst the other, the " toxophore " group, is readily 

 decomposed. The haptophore group attaches itself 

 to the attacked cell and thus enables the toxophore 

 group to exert its specific action. The living 

 molecule of protoplasm is also regarded as con- 

 sisting of two parts, a central group with attached 

 unsaturated side-chains with which the haptophore 

 groups of toxines combine. Side-chains are then 

 generated to replace those fixed by the toxine, and 

 these being formed in excess of the requirement, 

 circulate in the blood forming the specific immune 

 substances or anti-toxines. Now, on introducing 

 such immune sera into the blood of another animal, 

 these free side-chains attach themselves to the 

 haptophore group of any toxine subsequently 

 gaining admittance, and at the same time combine 

 with an active principle the " addiment." This is 

 normally present in the blood, but in too dilute a 

 form to have much effect upon a toxine ; but when 

 thus concentrated by means of the side-chains it is 

 enabled to destroy the intruding substance by 

 means of its " zymophore " group. In support of 

 this view Ehrlich points out that when serum con- 

 taining the immune body or side-chains is heated 

 to 55° C. it loses its power of destroying bacterial 

 poison, but regains it after the addition of ordinary 

 serum containing no immune substance, but only 

 the hypothetical " addiment." 



Immunisation of Milk to Eennet.— The 

 discovery of the specific ferment which coagulates 

 milk was made by Heintz in 1872, and it was 

 subsequently isolated by Hammarsten from the 

 stomachs of numerous animals. It becomes in- 

 active when heated to 63° C. in a neutral solution, 

 but is uninjured by cooling to 0° C. Its activity 

 is measured by the time required by a given 

 quantity of rennet to coagulate a definite quantity 

 of milk. This time is nearly inversely proportional 

 to the amount of ' ferment. The most active pre- 

 parations obtained by Hammarsten coagulated 

 4.800,000 times their weight of casein from the 

 milk ; but beyond a certain point a further addition 

 of the ferment caused no acceleration. Morgenroth 

 has recently made the remarkable discovery that 

 on injecting rennet in gradually increasing minute 

 amounts into animals an anti-rennet is apparently 

 formed in the serum, and on adding the latter to 



ordinary milk, coagulation by rennet is prevented 

 or retarded. The strongest immune serum obtained 

 by Morgenroth .prevented coagulation, when 

 added in the proportion of 2 per cent, to milk 

 into which 1 part of rennet in 20,000 was subse- 

 quently introduced. In ordinary milk coagulation 

 occurred when rennet was added in the proportion 

 of 1 in 3,000,000. If we apply Ehrlich's side-chain 

 theory to this phenomenon, we must regard the 

 rennet introduced into the serum as attaching 

 itself by its " haptophore " group to the side-chains 

 of the protoplasmic cells. Side-chains are then 

 generated in excess and diffused throucrh the 

 serum, forming the immune substance or anti- 

 rennet. Ordinary milk, according to this theory, 

 contains an " addiment " which is too dilute to 

 have much action upon rennet; but on treating 

 the milk with the immune serum, the anti-rennet 

 attaches itself to this " addiment." and thus enables 

 it to concentrate its " zymophore " group upon the 

 intruding rennet, and destroy it. 



Arsenic on Malt. — Some interesting particulars 

 on this subject were given by Mr. W. Thomson. 

 Public Analyst for Stockport, in a recent lecture 

 before the Society of Arts. He stated that owing 

 to the method in which malt was dried, arsenic 

 must have been present in beer for more than a 

 century. The germinated barley was dried by 

 means of anthracite or coke, and some of the 

 arsenic which was volatised from the fuel, even 

 when there was no smoke, condensed upon the malt. 

 In one case he found ordinary soot to contain 

 1-5 grain of arsenic to the pound, or 22J times the 

 maximum dose, its origin being probably the pyrites 

 in the coal. In anthracite coal he detected from 

 Too *° ^5 S' ram P er pound, whilst coke contained 

 from \ to t 1q grain. Of sixty-two samples of malt 

 which he examined, only seven were quite free from 

 arsenic, the others containing from -} <5 to = grain. In 

 the latter case, if the whole of the arsenic present 

 passed into the beer, about i grain per gallon 

 would be present — a serious amount. It has been 

 found, however, by Mr. A. C. Chapman, Secretary 

 of the Society of Public Analysts, that a con- 

 siderable proportion of the arsenic on malt is taken 

 up by the yeast during the fermentation, whilst 

 another part is possibly precipitated on boiling tin- 

 wort. A member of a firm of malsters informed 

 the writer that a sample of malt which had been 

 found to contain arsenic was mechanically brushed 

 and again submitted to the analyst, who now cer- 

 tified it to be free from contamination. The 

 evidence, however, on this point is conflicting. 



The Blood of Different Animals.— In the 

 March issue of the " Bulletin de la Society 

 Chimique de Paris " M. S. Cotton describes some 

 interesting observations which he has made, on the 

 well-known property possessed by blood, of libe- 

 rating oxygen from hydrogen peroxide. On treat- 

 ing 1 cubic centimetre of blood with 250 c.c. of 

 hydrogen peroxide the following quantities of 

 oxygen in c.c. were collected : — 



Minimum. Maximum. 



Man 580 .. 610 



Horse .. . .. 320 350 



Pig 320 . . 350 



Ox 165 .. 17(1 



Guinea-pig .. .. .. 115 .. 125 



Sheep GO 65 



The blood of female and young animals gives 

 somewhat higher results than old male animals. 



