July 18, 1884.] 



SCIENCE. 



59 



"Without manure 



With nitrogen 



With potash and phosphoric acid, 



With potash, phosphoric acid, and 



nitrogen 



Dry matter. 



13.5 grams. 



15.3 " 

 17.0 " 



24.4 " 



Containing 

 nitrogen. 



0.23 grams. 

 0.26 " 

 0.29 " 



0.41 " 



The nitrogen of the unmanured soil was not suf- 

 ficient to fully supply the needs of the barley; for 

 while manuring with potash and phosphoric acid only 

 enabled it to produce 26% more dry matter, contain- 

 ing 0.06 of a gram of nitrogen, the addition of 0.2 of 

 a gram of soluble nitrogen enabled it to show an 

 increase of 81% of dry matter, containing 0.18 of a 

 gram of nitrogen. 



These facts admit of but one conclusion; viz., that 

 peas are able to assimilate the nitrogen contained in 

 the soil much more readily than is barley. The fact 

 that the pea-plant contains much more nitrogen than 

 the barley-plant does not show that peas should receive 

 much more nitrogenous manure than barley, but, on 

 the contrary, that they can readily supply themselves 

 with nitrogen, but need to be manured with potash, 

 and particularly with phosphoric acid. Barley, on the 

 other hand, contains little nitrogen, partly because it 

 cannot gather it readily, and therefore it needs an 

 artificial supply. In other words, the greater need 

 of nitrogen on the part of the peas corresponds to a 

 greater power of obtaining it. 



It is, of course, unsafe to generalize from these 

 two experiments. At the same time, their results 

 correspond so exactly with the teachings of experi- 

 ence regarding the most suitable manuring for 

 legumes and cereals respectively, and appear a priori 

 so probable, that one can hardly avoid a strong belief 

 in their general application. They certainly open an 

 interesting and important field for further research. 

 If it can be shown, that, in manuring any given plant, 

 we ought to direct our attention more particularly to 

 those elements of its food which it contains in rela- 

 tively small quantity rather than to those present in 

 abundance, we shall have made a very considerable 

 advance in our knowledge of the theory of manures. 



H. P. Armsbt. 



KOCH'S WORK UPON TUBERCULOSIS, 

 AND THE PRESENT CONDITION OF 

 THE QUESTION. 



The question of the cause of that form of disease 

 known as tuberculosis is one which has been the 

 subject of discussion in medical circles for many 

 years. It is of especial interest to the laity, because 

 in one of its forms it includes the affection so widely 

 known as consumption of the lungs, or phthisis. 

 The idea of a contagious nature as belonging to this 

 process, i.e., to tuberculosis, was first broached in 

 modern times by Yillemin, 1 as the result of a series of 



1 Gazette medicate de Paris, December, 1865. fitudes sur la 

 tuberculose. Paris, 1868. 



experiments upon animals, conducted by him. These 

 experiments attracted very great attention at the 

 time, and were subsequently repeated, with varying 

 degrees of success and failure, by numerous observ- 

 ers. Twenty-five years before Villemin's experiments 

 were announced, Klencke 1 claimed to have produced 

 tuberculosis in animals (rabbits) by the inoculation 

 of tuberculous matter. His results do not, however, 

 seem to have received the attention which they de- 

 served; and it is to Yillemin that is usually ascribed 

 the beginning of the line of experiment which has 

 resulted in the work which is under consideration 

 to-day. 



Among those who have taken up the question of 

 the specific nature of tuberculosis in inoculation ex- 

 periments, may be especially mentioned Waldenburg, 

 Klebs, Cohnheim, Frankel, and Baumgarten. In- 

 halation experiments, in which the disease is sought 

 to be communicated by forcing animals to inhale 

 finely divided dried tuberculous materials, have been 

 tried again and again with as conflicting results as 

 in the preceding series. Those who have done the 

 most noteworthy work in this direction are Schot- 

 telius, Tappeiner, Weigert, Weichselbaum, and 

 Balogh. 



Feeding-experiments form the third class by which 

 an endeavor to obtain evidence for or against the 

 specific nature of tuberculosis has been made. It is 

 unnecessary to do more than mention the names of 

 a few of those who have taken a prominent part in 

 this branch of the investigation : such are Aufrecht, 

 Klebs, Bollinger, Colin, Tappeiner, and Toussaint. 



These names, forming but a small part of the cata- 

 logue of those who have been interested in the study 

 of tuberculosis, will give some indication of the vast 

 amount of work done, and the interest taken in this 

 subject. 



After Yillemin' s experiments, and coincident with 

 all the work that was called out by them, the ques- 

 tion of the nature of the virus of tuberculosis was 

 eagerly discussed. The idea of a contagium vivum 

 was first suggested by Buhl, 2 who claimed to have 

 observed micro-organisms constantly occurring in tu- 

 berculous nodules ; these micro-organisms being both 

 micrococci and bacteria. This idea was taken up by 

 Klebs, 3 who claimed to have isolated a micrococcus 

 by culture, and to have produced tuberculosis by the 

 inoculation of this organism. Klebs' s experiments 

 were repeated, and with the same, or nearly the same, 

 successful results, by Schneller, 4 Reinstadler, 5 and 

 Deutschmann. 6 The acceptance of this monas tuber- 

 culosum, as it was called, as the specific cause of the 

 tuberculous process, was not general, however; and 

 for various reasons the work of Klebs seems to be 

 untrustworthy. 



1 Untersuchungen un erfahrungen, etc. Von Professor 

 Klencke. Leipzig, 1S43. Bd. i. 



2 Lungenentzundung, tuberculose, und sehwindsueht, 1ST3. 



3 Prager med. wochenschrift, 1S77, Xos. 42 and 43. 



4 Ueber therapeutische versicche. Arch, fur exp. pathol.,h&. 

 xi., 1879. Exp. und histolog. untersuchung iiber die entstehiaig 

 der tuberculose, etc., 1S80. 



5 Arch, fur exp. pathoL, bd. xi., 1S79. 

 e Med. centralblatt, No. IS, 1SS1. 



