September 28, 18S3.] 



SCIENCE. 



435 



precipitation of the organic material in the nutritive 

 medium rather than to any direct action ui)0n the 

 living organisms, which, as we have seen, are not 

 killed by a far greater quantity of the reagent. 



Tlie conclusions at which Dr. Sternherg arrives, 

 are. tliat the vital resistance of bacterial organisms 

 to chemical reagents differs, within certain limits, for 

 different species. And certain species show special 

 susceptibility to the germicide action of particular 

 rcigents; e.g., the septic micrococcus to alcohol, and 

 B. ternio to boracic acid. 



There is, therefore, reason for supposing that dif- 

 ferent pathogenic organisms may differ in like manner, 

 as to susceptibility to the action of various reagents 

 administered medicinally with a view to their de- 

 struction. Nevertheless, the comparative germicide 

 value of the reagents tested is tlie same for tlie sev- 

 eral test-organisms, and, allowing certain limits for 

 specific peculiarities, it is safe to generalize from the 

 experimental data obtained in the practical use of 

 these reagents as disinfectants. But it must be re- 

 membered that the resisting power of reproductive 

 spores is far greater than that of bacterial organisms 

 in active growth (multiplication by fission), and the 

 data obtained for the latter cannot be extended to in- 

 clude the former. 



The antiseptic value of the reagents tested depends 

 upon their power to prevent the multiplication of 

 putrefactive bacteria; and this is not necessarily con- 

 nected with germicide potency, for some reagents 

 which fail to kill these micro-org.inisms are, never- 

 theless, vahiable antiseptics, e.gf. ferric sulphate and 

 boracic acid. 



Clinical experience has demonstrated the value of 

 all the potent germicide reagents tested in one or 

 more of the diseases which there is the most reason 

 to believe are due to the presence of pathogenic 

 micro-organisms in the primae tiae, in the blood, or 

 in the tissues; e.g., intermittent-fever, typhoid-fever, 

 dysentery, erysipelas, syphilis, etc. The 'germ-the- 

 ory' as to the causation of these diseases receives, 

 tlierefore, very strong support from modern thera- 

 peutics: but the experiments do not justify the belief 

 that any one of the reagents tested can be admin- 

 istered as a specific in germ-diseases generally. This 

 also accords with the results of clinical experience, 

 and makes it possible to believe that the specific, self- 

 limited diseases are also ' germ ' diseases. 



LETTERS TO THE EDITOR. 

 The practical value of soil-analysis. 



Is Bulletin Ivi. of the New York agricultural ex- 

 periment-station. Dr. Sturtevant gives the re.isons for 

 which the station declines to make soil-an.alyses 'for 

 the purposes of the individual farmer:' stmimarizing 

 them in the statement that such ayalyses " can offer 

 no solution of the problem of what fertilizer, and how 

 much, to apply." 



Were this statement made in a somewhat less gen- 

 eral and .absolute manner, I should have no fault to 

 find with it: for in the case of the long-oultivated 

 fields of the state of New York, which have been sub- 

 ject to indefinitely varied culture-conditiohs and the 

 use of fertilizers, the cases in which chemical analysis 



alone would point with any degree of certainty to the 

 true cause of failure to produce profitable crops would 

 be exceptional; and the station would be likely to be 

 overrun with requests for an indefinite amount of 

 comparatively useless routine work. 



But when Dr. Sturtevant bro.idly adds his denial 

 " th.it analyses of soils can give us definite informa- 

 tion concerning their productiveness," lie seems to go 

 beyond the limits justified by the record, and beyond 

 what the context following would appear to show he 

 intended to say. If tlie clause above quoted were 

 to read, instead, " while denying that analyses of cui- 

 tivaled soils can give us definite information regarding 

 their;}re.<fH( productiveness." I should agree with him 

 so far as the great majority of cases is concerned, — so 

 much so, that it is only exceptionally that 1 under- 

 take the analysis of a cultivated soil, but usually go 

 back to its virgin ancestor for information as to its 

 general character; and from this, and the usually sim- 

 ple history of its cultivation, pretty definite inferences 

 as to the prominent wants even of a cultivated soil 

 can in very many cases be deduced, as is proved by 

 the practical results. Dr. Sturtevant's own statement 

 as to the frequency and consequent practical impor- 

 tance of such inquiries would seem to justify the tak- 

 ing of some pains to approach its solution, before 

 jiroclaiming an absolute non possumUK. 



As for virgin soils, which over wide areas liave beet» 

 subject to uniform or uniformly variable conditions, 

 it is apriori reasonably presumable, and I think expe- 

 rience confirms the inference, that, otherthings being 

 equal, the amount of available plant-food, and there- 

 fore the durability of a given soil under the usual 

 culture, witliout replacement, is sensibly proportional 

 to the plant-food percentages shown by the usual 

 method of analysis. Whether or not other things are 

 really equ.al can only be ascertained by intelligent 

 examination in the field as well as in the laboratory ; 

 .and soil-specimens taken by non-experts rarely fulfil 

 this condition. 



While, therefore, believing that Dr. Sturtevaut's 

 action in this matter is well advised under the cir- 

 cumstances, I nevertheless believe that my contrary- 

 practice in regions but sparsely or recently settled is 

 at least equally well justified, and that the impor- 

 tance of affording the settler at least an approximate 

 insight into the present and ultimate durability of his 

 soil, and its general character and adaptations, is so 

 great as to justify a considerable public expenditure, 

 upon a well-considered plan carefully carried out by 

 competent persons both in the field and in the labo- 

 ratory, even with our present limited knowledge of 

 the chemistry of soils — which, I cannot but remark, 

 is not likely to be increased very rapidly if tlie com- 

 position of soils serving for culture-experiments con- 

 tinues to be ignored, as has so largely been the case 

 heretofore. The prime importance of the presence 

 of a certain minimum percentage of lime, for exam- 

 ple, is manifestly so great, that no experimenter can 

 afford to be ignorant of the presence or absence of a 

 proper supply of that substance in his soil ; and the 

 cases in which analysis shows the extreme scarcity or 

 extreme abundance of lime, phospliates, or potash, in 

 virgin soils and subsoils, are far more. fre(|uent th.an 

 the contemners of soil-analysis suppose. In the 

 former case the practical value of the indication is 

 too obvious to be overlooked, and is amply attested 

 by the results following the application, e.g., of phos- 

 phate fertilizers in such cases. We might not be able 

 to detect the addition thus made to the phosphates of 

 the soil by the most careful analysis; but the fact 

 that the soil is naturally poor in phosphates will re- 

 main a fruitful truth forever after. 



