August i8, 1898] 



NATURE 



569 



colour tests as Millon's, nitric acid, &c., have no real 

 value ; the colour developed may be due to the proteid 

 molecule as a whole, but more probably to some de- 

 composition product, and, as already mentioned, some 

 colloids which bear no relation to actual proteids give 

 reactions considered characteristic of these substances. 

 Again, the peptons in their reactions strangely recall the 

 alkaloids, especially in the precipitates they give with 

 mercuric chloride, potassium periodide, phosphotungstic 

 and phosphomolybdic acids, &c., while elementary 

 analysis is of little value, as all the proteids give very 

 similar figures, which in nowise indicate the striking 

 differences met with in their physiological behaviour. 

 When, in addition, it is remembered how extremely 

 complex and mobile the proteid molecule must of 

 necessity be, and the readiness with which changes in 

 its constitution are brought about, something more than 

 a few empirical colour and physiological tests will be 

 required to convince chemists that pepton has been 

 actually synthesised. Dr. Lilienfeld's "results evidently 

 need further investigation, and in the meantime the 

 question raised by his announcement is distinctly one 

 that calls for suspended judgment. 



Sidney Williamson. 



THE TOXICITY OF EEL-SERUM, AND 

 FURTHER STUDIES ON IMMUNITY. 



'T'HE investigation of poisons, both bacterial and 

 *■ animal, has been pursued with such enthusiasm in 

 so many parts of the world during the past decade, and 

 the public have been brought into such close touch with 

 some of the practical applications which have followed in 

 the track of these investigations, that the term toxin and 

 anti-toxin, unknown in the days of Dr. Johnson's colossal 

 dictionary, may now without exaggeration be said to 

 form part of the vocabulary of every well-ordered 

 household. 



But whilst the more striking beneficent results obtained 

 in the study of immunity have become public property, so 

 to speak, a mass of important and most interesting re- 

 searches remain concealed from the layman's view, locked 

 away, as far as he is concerned, in the pages of divers 

 scientific journals. 



Of such researches we may cite those which have re- 

 legated the blood-serum of eels to the category of 

 poisons. This remarkable discovery was made as long 

 ago as the year 1888 by A. Mosso,i of Turin, who 

 found that the serum of eels, when subcutaneously and 

 intravenously inoculated into animals produced fatal re- 

 sults, although it was quite harmless when introduced 

 per OS. Half a cubic centimetre of eel-serum inoculated 

 into a dog weighing 14 lbs. killed the animal in seven 

 minutes ; and Mosso obtained similarly lethal results in 

 the case of rabbits, guinea-pigs, frogs, and pigeons. 



But little further attention appears to have been paid 

 to this subject until Calmette,- in 1895, and Phisalix,^ in 

 1896, carried out further experiments on the toxic 

 character of such serum from an immunising point of 

 view, and this year we have had quite a crop of memoirs 

 on eel-serum treated from various sides, and our in- 

 formation is consequently greatly extended concerning 

 both the character of this poison and its antidote. 



It appears that the toxic effect of this eel-serum varies 

 according to the manner in which it is introduced into an 

 animal, and the different quantities required to produce 

 lethal subcutaneous, intravenous, and intraperitoneal in- 

 oculations respectively have been elaborately determined 

 by Maglieri,* who states that for every 2-lb, weight of 



1 Archives Italienncs de Biologic, vol. x., 1888. 



■■* " Venins, toxines et scrums antitoxiques " (Annales de r Institut 

 Pasteur, vol. ix., 1895). 



3 Comptesrendus de t Acadimie des sciences, 1896. 



* " Sull'azione tossica immunizzante e battericida del siero di sangue di 

 anguilla." (Annali dlgiene Sperimcntale, 1897.) 



rabbit employed from "02 to 025 c.c. of serum is required 

 in intravenous inoculations, '4 to '45 c.c. in subcutaneous 

 inoculations, and '20 to "25 c.c. in intraperitoneal inocula- 

 tions. Hericourt and Richet^ mention that in their 

 experiments 'i c.c. intravenously introduced was fixed as 

 the lethal dose of serum for a rabbit weighing 4 lbs. 



Wehrmann,^ however, remarks that it is in reality very 

 difficult to lay down a general law as to the exact quantity 

 of this serum which will constitute a fatal dose, for it not 

 only varies in toxic strength at different times of the year^ 

 but in eels of different origin ; and it is, therefore, neces- 

 sary to determine the toxic value of such serum each 

 time a fresh supply is collected. 



Before passing on to the experiments which have been 

 carried out on modifying the lethal activity of this eel-serunv 

 and on artificially protecting animals from its toxic action, 

 we may refer to some interesting investigations made by 

 Maglieri {loc. cit.) to ascertain whether such serum is 

 endowed with any bactericidal properties. For this pur- 

 pose tubes containing eel-serum were inoculated with 

 colon bacilli (i?. coli communis)., cholera vibrios, and. 

 dipththeria bacilli respectively ; after different intervals 

 of time, varying from fifteen minutes up to twenty-four 

 hours, gelatine and broth tubes were inoculated from all 

 the serum-tubes. In every case a positive result was 

 obtained ; that is to say, growths of the three different 

 microbes employed subsequently appeared in all the 

 gelatine and broth tubes, indicating that, however lethal 

 this eel-serum may be in regard to animal life, these 

 minute vegetables — or, at any rate, the three varieties 

 above mentioned — enjoy a natural immunity from its 

 toxic action. 



The quantity of blood which is procurable from even a 

 large eel weighing about 5 lbs. is very small, never more 

 than 25 cubic centimetres, and this only yields fronv 

 10 to 12 c.c. of serum, whilst in the case of vipers a 

 relatively large quantity of blood is obtained. This eel- 

 serum, according to Wehrmann, can be kept in a fit 

 experimental condition for two weeks if stored over ice 

 and in the dark, but Maglieri states that its toxicity- 

 declines gradually after the eighth day of its collection 

 even when protected from light. 



As regards the artificial modification of the lethal 

 properties of eel-serum, U. Mosso,^ a brother of the 

 Mosso already referred to, mentions, amongst other 

 devices, that heating the serum to from 68^ to 78^ C. 

 removed its toxic character. Phisalix {loc. cit.) also- 

 found that heating it to 58° C. for a quarter of an hour- 

 destroyed its toxicity, and that such heated serum was 

 capable of endowing animals with immunity towards 

 ordinary eel-serum, this immunity being, however, of a 

 very transitory character. Wehrmann found that ex- 

 posing it to this temperature for a quarter of an hour 

 removed the greater portion of its toxic powers, and 

 when animals were inoculated with serum thus treated, a 

 somnolent state, sometimes accompanied by a depression^ 

 of temperature, followed, but that they recovered their 

 normal condition at the end of from two to three hours,, 

 having meanwhile acquired a certain degree of immunity 

 from the effect of ordinary eel-serum inoculations, which 

 was retained for three days. Maglieri found that pre- 

 serving eel-serum at a constant temperature of only 37° 

 C. for the space of twenty-four hours was sufficient to- 

 greatly modify its toxicity. Very interesting is the ob- 

 servation recorded by Wehrmann that by subcutaneously 

 inoculating anti-venomous serum * into eels the toxicity 

 of their blood is considerably reduced. Thus an eel 

 weighing about half a pound was inoculated with 5 cubic 



1 Compies rendus de /a SociiU de Biologie, 1897. 



2 " Recherches sur les propriit^ toxiques et antitoxiques du sang et de la 

 bile des Anguilles et des Viperes" (Annates de rinstilut Pasteur, p. 810,. 

 1807.) 



3 Archives Itatiennes de Biotogie, 1889. 



* Serum derived from an animal rendered artificially immune to the 

 poisonous action of snake-venom. 



NO. 1503, VOL. 58] 



