20 



NATURE 



[September 2, 1915 



tions upon the red blood-corpuscles, and of the signi- 

 ficance of these results with regard to the functions 

 of the body. These researches on the red blood- 

 corpuscles, which introduced physical chemistry into 

 medical science, were confined to the study of their 

 chemical and volumetrical alterations. 



But the influence of the salt solutions on the very 

 life of the cells could not well be tested on those parti- 

 cular objects, although systematically investigated. We 

 have felt this from the beginning, and repeatedly asked 

 ourselves whether the solutions producing the chemical 

 and volumetric changes of the red blood-corpuscles 

 had or had not seriously damaged these cells, and 

 thus, whether it was possible to apply the conclusions 

 arrived at to problems regarding life itself. Therefore, 

 wherever it was possible, we examined whether the 

 phagocytes, being submitted to the same agencies, 

 kept their phagocytarian power. This was always the 

 case. This conclusion enhances the value of our re- 

 searches on the red corpuscles, the more so because 

 the chemical -and volumetric alterations of the white 

 cells corresponded with those of the red ones. But 

 a systematic study of the life of the leucocytes had 

 not, previous to our researches, been undertaken, and 

 this is rather surprising. 



II. — Method of Investigation. 



Our method has been very simple. White corpuscles 

 '(leucocytes) from the blood of a horse are transferred 

 to various media mixed with very small particles of 

 carbon. After having stood some thirty minutes in 

 an incubator at body temperature a great many of 

 the cells have eaten up carbon. Microscopical pre- 

 parations are made, and it is ascertained what per- 

 centage of the leucocytes has taken up carbon. This 

 percentage is the measure for the degree of phago- 

 cytosis and gives the value of the influence of the 

 various agents used on that function of life. 



Suppose in examining 600 leucocytes lying in their 

 natural medium (blood serum) I find that 300 of them 

 "have taken up carbon, the percentage of phagocytosis 

 can then be expressed by 300/600x100 = 50 per cent. 

 In order to examine, for instance, the influence of 

 small amounts of acid, I add this substance to the 

 serum and repeat the same experiment under the 

 same conditions. I now find that of the 540 examined 

 leucocytes only 200 have taken up carbon. The 

 phagocytosis is now expressed by 200/540x100 = 37 

 per cent. Thus the addition of acid to the serum 

 has lowered phagocytosis. 



This calculation is based on the principle that the 

 phagocytic power of the individual phagocytes present 

 in a suspension is unequal, a fact which cannot be 

 wondered at when we take into consideration that 

 they are of diff'erent age. The more detrimental the 

 action of the agent, the smaller should be the number 

 of phagocytes which take up carbon in the same space 

 of time. 



Our selection of an indifferent substance such as 

 carbon instead of bacteria, was based upon the fact 

 that we otherwise feared our work would become too 

 complicated. We here refer to the fact established by 

 Sir Almroth Wright and his school that most kinds 

 of bacteria, before they can be taken up by the phago- 

 cytes, must undergo a certain amount of sensitisation. 

 Hence it follows that the intensity of phagocytosis will 

 not only be influenced by the agent, as such, but also 

 by the degree of " sensitisation " the particles have 

 undergone. Another fact which had to be borne in 

 mind was that the bacteria sometimes secrete poisons, 

 which have an injurious effect on the phagocytosis. 

 Even dead bacteria contain poisons. 



The selection of carbon as an indifferent substance 

 instead of the usual grains of carmine was based upon 



NO. 2392, VOL. 96] 



the greater facility and accuracy with which the 

 taking up of carbon can be ascertained. I shall not 

 here give a detailed description of the method of 

 obtaining the leucocytes, or of preparing the carbon, 

 or of the method of determining the percentage of cells 

 which have eaten carbon. I prefer to give some of 

 the more striking results. 



III. — Results. 



(i) The Influence of Small Amounts of Calcium. 



In examining systematically the influence of the 

 addition of small amounts of various salts (ions) to the 

 blood-serum, it was found that very small quantities 

 of calcium increased the phagocytosis to a consider- 

 able extent. An addition, for instance, of 0-005 P^"" 

 cent, of chloride of calcium (CaClj) to the natural 

 medium (serum) caused an increase of about 22 per 

 cent, in the phagocytic power. This favourable effect 

 becomes even more strongly manifest when, instead 

 of being added to the suspension of phagocytes in 

 serum, the calcium is added to a suspension of phago- 

 cytes in a solution of chloride of sodium (common 

 salt), in which phagocytosis occurs almost to the same 

 extent as in serum. 



These investigations have been continued in two 

 directions. In the first place, we asked ourselves 

 whether the influence of calcium would also manifest 

 itself in the living body. Ail experiments had hitherto 

 been made outside the body. It will be remembered 

 that on placing under the skin (for instance, on the 

 inside of the thigh of a rabbit) small capillary tubes, 

 closed at one end and filled with an extract of bacteria 

 in a solution of chloride of sodium, phagocytes enter 

 these tubes. This phenomenon is called Chemotaxis, 

 and is based upon the creeping movement of the 

 phagocytes towards the excretions and secretions pro- 

 duced by the bacteria. 



After a certain lapse of time, the open part of the 

 capillary tube is filled with a white column consisting 

 of phagocytes. If, in fact, calcium promotes the 

 activity of the phagocytes, not only in the phago- 

 cytic process described above, but also in the living 

 body, we argued it might be expected that by calcium 

 that mobility of the cells, which here finds its expres- 

 sion in chemotaxis, would be accelerated. Therefore 

 we determined the length of the white column formed 

 in the capillary tube with animals, either treated with 

 calcium or not so treated. 



We expected to find that in rabbits treated with 

 calcium the white column would after the same space 

 of time be longer than in animals not having been 

 treated with calcium. We have used two methods, 

 which gave the same result. I will mention one only. 

 It consisted in injecting into the rectum of two series 

 of animals a solution of chloride of sodium mixed for 

 one series with calcium, and for the other without 

 calcium, and then examining the length of the column 

 of phagocytes penetrating into the capillary tubes. 



The difference between the two series was con- 

 siderable. The calcium-rabbits showed the greatest 

 degree of chemotaxis, although the amount of chloride 

 of calcium used was very small, viz., o-o6 gr., a 

 quantity corresponding with that given to man in 

 mineral waters rich in calcium. Let us add that a 

 natural mineral water used in our experiments gave 

 the same results as the chloride of calcium solution. 



What can be said of the mechanism of this effect? 

 The calcium, on being absorbed by the mucous mem- 

 brane of the rectum, enters the blood-circulation and 

 by this is carried into the lymoh of the tissue-spaces ; 

 where the glass capillary tubes are placed. The 

 phagocytes which are there will soon undergo the 

 stimulating influence of the calcium thus introduced, 

 i.e. their mobility will be increased and chemotaxis 

 will be promoted. 



