September 2, 1915] 



NATURE 



19 



an opportunity of discussing^ the matter, came to the 

 conclusion that the symptoms which had alarmed 

 growers were attributable to bad cultivation and 

 water-logging- of the soil. 



Since 19 13 the experimental work commenced by 

 Mr. Parnell at the now abandoned Indigo Research 

 Station at Sirsiah has been continued at Pusa by 

 Mr. and Mrs. Howard, whose work, as detailed in 

 their First Report for 1914, has satisfactorily disposed 

 of the unfounded dread that East African indigo had 

 in India fallen a victim to some mysterious malady. 

 In this and in their Second Report for 1915, the 

 authors have further shown planters how a recurrence 

 of the difficulties experienced since 19 10 may be 

 avoided, and have taught them that a treatment with 

 which they were familiar as regards Malayan indigo 

 calls for modification when the East African plant is 

 in question. But they have done more than this; in 

 the words of a writer in the Allahabad Pioneer, one 

 result of the work of Mr. and Mrs. Howard is that 

 "one bugbear of the Java indigo planter — the 

 impossibility of obtaining good seed — is on the high- 

 way to being removed." The beneficial effect of their 

 work, however, does not end here; in their Second 

 Report they point out with a directness to which the 

 planting community have not been accustomed, that 

 the future of their industry in Bihar will depend on 

 their ability to increase the yield of indigo from the 

 plant. If the advice given in the Report for 19 15 

 be followed, there may still be some hope as to the 

 future in store for the industry, the object of which 

 is the production of natural indigo. It is true, as 

 the sympathetic writer in the Pioneer remarks, that 

 many improvements will be necessary if this industry 

 is to re-establish itself. The friends of the Bihar 

 planter — he has, and he deserves to have, many— for 

 years past have urged this necessity upon him, and 

 it is but fair to say that he has taken the advice to 

 heart. But his most genuine well-wishers have not 

 hesitated to remind him that, so far, he has failed 

 in one important particular — he has not recognised, 

 as he might, his own limitations. His "associa- 

 tions" and his "syndicates" serve many legitimate 

 and useful purposes. But the direction of research 

 in connection with indigo has clearly not been their 

 metier, and if the two Reports by Mr. and Mrs. 

 Howard enable this truth to be realised they will 

 have done good which should outweigh even the 

 immediate material benefit which they confer on a 

 singularly deserving community. 



For his attitude towards the plant and its product 

 the indigo-planter is not wholly to blame. The 

 stranger can teach him little with regard to the culti- 

 vation of the particular plant with which he is 

 familiar. To his colleague the chemist there is, after 

 all, but one indigo. When the indigo-planter knows, 

 as the botanist tells him, that among the forty kinds 

 of tobacco, the twenty kinds of wheat which surround 

 his dwelling, he has to do with but one species of 

 Nicotiana and one of Triticum ; when he observes 

 that it is easy to find two tobaccos and two wheats 

 differing in outward characters more markedly than 

 any two indigo plants of his acquaintance do; it is 

 scarcely surprising if he be influenced by a sub- 

 ''nnscious belief that, after all, the indigo plants may 

 only forms of one Indigofera, and that the treat- 

 iit suitable for one may well serve for another. 

 r is it quite certain that the botanist, whose task 

 i>; to keep the planter right, is always free from a 

 nilar unwitting prejudgment. The tangled syno- 

 iny with which the history of these tinctorial species 

 Indigofera is loaded, and the instinctive tendency 

 suggest that each new one may be a modified 

 m of 7. tinctoria, point to this possibility. That 



NO. 2392, VOIv 96] 



this is not the case those who have grown the different 

 tinctorial species together and have compared them 

 at various stages of growth can testify ; those who 

 have made a critical herbarium study of the material 

 available express the same judgment. Even in such 

 as have not enjoyed these opportunities, a considera- 

 tion of the history of these tinctorial indigos from a 

 botanical point of view may perhaps induce a reserva- 

 tion of judgment. The hope of effecting this, and the 

 desire to assist the planter to realise that the dis- 

 placement of one indigo plant by another is nothing 

 new and has never been unreasoned, may serve as 

 an excuse for the rdsumi of these displacements here 

 given. 



RESEARCHES ON PHAGOCYTOSIS. 

 I . — Introduction . 

 A LTHOUGH the number of the white blood- 

 -^~*- corpuscles, compared with that of the red, is 

 small (i leucocyte to ±350 red blood-corpuscles), the 

 absolute number of them is rather considerable; for 

 in the five litres of blood, which is the usual quantity 

 for a man of normal size, there are 80,000,000,000 

 leucocytes. 



A part of these leucocytes has, owing to their plas- 

 ticity, the property of enveloping and in this way 

 taking up all sorts of particles, as, for instance, coal- 

 dust, grains, and also bacteria. It is because of this 

 property that these cells, which have a diameter not 

 larger than about 0008 of a millimetre, have engaged 

 our attention, especially since Metchnikoff has estab- 

 lished that bacteria englobed by these cells are killed 

 in them, and are thus made innocuous to our body. 

 For this reason he has called them phagocytes (eating 

 cells), and their process of eating phagocytosis. 



The life of these cells deserves our interest; but 



until now it has not been, as such, the object of a 



\ systematic investigation, a fact Metchnikoff himself 



I regretted in a paper he read some years ago to the 



' students of the University of Amsterdam on 



" Reactions Phagocytaires." * 



Now I must confess that the importance of the 

 phagocytes for the defence of our body against bac- 

 teria has not been the first and principal reason of my 

 investigations with these cells : the principal reason 

 was their being an excellent object for researches of a 

 general biological nature. 



I think a physiologist in the first place must practise 

 science for its own sake, not asking whether his work 

 may be of immediate practical use, but should he, 

 however, accidentally stumble upon an idea which may 

 be directly used for the bodily welfare of mankind, 

 this should not prevent him from giving his attention 

 to this ; in fact, it is his duty to do so. 



The phagocytes are a suitable object for studying 

 life phenomena. In the first place, they are not such 

 complicated organs as the muscles, heart, brain, etc. ; 

 they are simple cells, easily isolated. Secondly, it is 

 possible to follow quantitatively the effect on their 

 life of slight alterations of their natural medium. 



It is obvious that the phenomena produced by the 

 agency of solutions not dangerous to life are, in fact, 

 nothing else but the effects of reactions which finally 

 will help us to penetrate further into the physical and 

 chemical structure of the living cell. 



The investigations on the life of phagocytes, which 

 during the last years have occupied myself and my 

 collaborators, are a continuation of researches begun 

 several years ago (1883) with the object of ascertain- 

 ing the influence of salt solutions of various concentra- 



1 Nous ne sommes qu'au cl*but. L^rsqu'on connaitra niieux laphysiologie 

 dfs phagocytes, en ch^rchera des m^lbodes pour augmenter I'sctiviirf de crs 

 ^'^ments dans la lutte centre let microbes et on iherchcra d'autres p ^ur pr^- 

 5erver contre I'attaque des phagocytes les cellules nobles de no re corps. 



