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Dr. Paul Ehrlich. 



relatively uncomplicated bodies; at least, by comparison with the 

 primary and complex albumins of which the living cell is composed. 

 If a cell of the organism has, with the assistance of an appropriate 

 " side-chain," fixed to itself a giant molecule, as the proteid mole- 

 cule really is, then, with the fixation of this molecule, there is pro- 

 vided one of the conditions essential for the cell nourishment. Such 

 giant molecules cannot at first be utilised by the cells, and are only 

 made available when, by means of a ferment-like process, they are 

 split into smaller fragments. This will be very efi'ectually attained 

 if, figuratively speaking, the " tentacle " or grappling arm of the proto- 

 plasm possesses a second haptophore group adapted to take to itself 

 ferment-like material out of the blood fluid. Through such complex 

 organisation, by which the " tentacle " acts also as the bearer of a 

 ferment-functioning group, this group is brought into close relation 

 with the prey destined to be digested and assimilated. 



For such appropriate arrangements, in which the " tentacular " 

 apparatus also exercises a digestive function — if it be permissible to 

 pass from the abstract to the concrete — we find analogies in the 

 different forms of insectivorous plants. Thus it has been known since 

 the famous researches of Darwin that the tentacles of Drosera secrete 

 a proteid-digesting fluid. 



If we now recognise that the difl'erent lysines only arise through 

 absorption of highly complex cell material — such as red blood cor- 

 puscles or bacteria — then the explanation, in accordance with what I 

 have said, is that there are present in the organism " side-chains " 

 of a special nature, so constituted that they are endowed not only 

 with an atomic group by virtue of the affinities of which they are 

 enabled to pick up material, but also with a second atomic group, 

 which, being ferment-loving in its nature, brings about the digestion 

 of the material taken up. Should the pushing-ofF of these "side- 

 chains " be forced, as it were, by immunisation, then the " side-chains " 

 thus set free must possess both groups, and will therefore in their 

 characteristics entirely correspond to what we have placed beyond 

 doubt as regards the " immune-body " of the hsemolysine. 



In this manner is simply and naturally explained the astonishingly 

 specialised arrangement that, through the introduction of a definite 

 bacterium into the body, something is produced which is endowed 

 with the power of destroying by solution the bacterium which was 

 administered and no other. This contrivance of the organism is to 

 be regarded as nothing more than a repetition of a process of normal 

 cell-life, and the outcome of primitive wisdom on the part of the proto- 

 plasm. 



In conclusion, I wish hastily to touch on only a few points. First, 

 to direct attention to the fact that the immunising sera produced by the 

 administration of bacteria are sometimes limited in their operation to 



