BLOOD SERUM. Ill 



leucocytes, which he proposes should be called alexocytes. Accord- 

 ing to his theory the pseudo-eosinophil granules constitute the parent 

 substance of the alexins. He succeeded in diminishing the number 

 of these leucocytes in the blood by the intravenous injection of leech 

 extract and found that the blood thus obtained was not equivalent to 

 normal blood in its germicidal properties. Denys ^ and his students 

 were among the earlier advocates of the theory that the alexins are 

 secretion products of the leucocytes. Buchner^ obtained leucocytes 

 in relatively large numbers by introducing, under aseptic precautions, 

 wheat gluten or aleuron into the pleural cavities of animals ; an 

 exudate rich in white blood corpuscles forms about the foreign body 

 after a few hours and the corpuscles thus obtained serve for experi- 

 mentation. The purpose of Bnchner's first experiments was to com- 

 bat the phagocytic theory of Metschnikoff, and he demonstrated that 

 the leucocytes, obtained as stated above, when destroyed by alternate 

 freezing and thawing, markedly increased the germicidal action of 

 the serum in which they were suspended, while at the same time they 

 were deprived of life. In other words, these experiments demon- 

 strated that the disintegration of white blood corpuscles liberates a 

 germicidal substance. Leucocytes obtained after Bnchner's method 

 can be freed from serum in the centrifuge, and may be dissolved or 

 suspended in physiological salt solution, distilled water, or in either 

 an active or an inactive serum. By experiments of this kind Hahn' 

 demonstrated that the addition of leucocytes to an active serum in- 

 creased the activity of the latter, while when added to an inactive 

 serum they restored its activity. In this way it has been shown 

 beyond controversy that blood serum owes its germicidal properties 

 to the white corpuscles. Numerous investigators have fully demon- 

 strated that the disintegration of the leucocyte is followed by the 

 liberation of alexins, and the most important question still unsettled 

 in this connection is whether or not the living white corpuscles 

 secrete alexins. Laschtschenko * has shown that either active or in- 

 active serum of the horse extracts alexins from the leucocytes of the 

 rabbit. This experiment was made in the following way : The 

 leucocytes were obtained in a pleural exudate, prepared after the 

 method of Buchner. This exudate was placed in a centrifuge and 

 the corpuscles separated from the serum. The corpuscles were then 

 repeatedly washed in the centrifuge with physiological salt solution 

 and after they had been thoroughly separated from all the constit- 

 uents of the serum they were well mixed with serum obtained from 

 other animals and freed from their own corpuscles by means of the 

 centrifuge. Both active and inactive sera were used in these experi- 

 ments. The result, which has already been stated, is attributed to 



' La cellule, 10, et seq. 



' Mwnehener med. Wochemchrift, 1894. 



'Archivf. Hygiene, 25. 



*Archivf. Hygiene, 37. 



