176 



SCIENCE 



[N. S. Vol. XXXVII. No. 944 



will take up his work at Berkeley next Sep- 

 tember. 



Dr. Eiciiard P. Strong, director of the 

 Government Biological Laboratory at Manila, 

 and professor of tropical medicine in the 

 Philippine Medical School, has been appointed 

 head of a newly established department of 

 tropical medicine in the Harvard Medical 

 School. 



DISCUSSION AND COKRESFONDENCE 



ON comparing ammonifying coefficients of 



different soils 



In the issue of Science for November 29, 

 1912, there appears on page 761 a special 

 article under the above caption by Professor 

 Chas. B. Lipman, of the University of Cali- 

 fornia. The brief is devoted almost entirely 

 to a friendly criticism of certain conclusions 

 drawn by the writer regarding a comparison 

 of the ammonifying efficiency of certain Colo- 

 rado soils with that of soils from other stated 

 localities. Such criticisms, when presented in 

 the proper spirit, and there is no reason to feel 

 that this has not been the case here, are always 

 welcome and are often helpful. 



Now, the writer admits quite freely that the 

 fundamental facts brought out by Professor 

 Lipman are very largely true. However, he 

 is not willing to concede so readily that the 

 criticisms based upon these facts as applied 

 to the case at hand are altogether warranted. 



Among Professor Lipman's comments is to 

 be found the following : 



Despite the fact that Professor Sackett makes 

 Bome qualifying statements in discussing the com- 

 parisons, he does not seem to attach importance 

 enough to some factors of which he appears to be 

 fully cognizant and gives no consideration to other 

 very important factors. 



In support of this statement, the critic 

 offers the following, all of which tends to leave 

 the impression that the writer has not taken 

 these matters into consideration and given 

 them due weight, in spite of the fact that 

 statements to the contrary appear in the orig- 

 inal publication^ referred to : 



' Bulletin 184, Colorado Experiment Station, 

 June, 1912, Part I., "The Ammonifying Efficiency 

 of Certain Colorado Soils. ' ' 



The writer (Lipman) of this note fails to appre- 

 ciate the value of a comparison of the ammonify- 

 ing powers of various soils as obtained by different 

 investigators whose methods vary as much as ours 

 do to-day. 



The writer in selecting the results of the 

 work of others for comparison was particular 

 to choose only such as were obtained in lab- 

 oratories where practically the same methods 

 have been employed, and wherever there has 

 been any departure from the procedure of the 

 majority, such departure has been indicated. 



On page 21 of the bulletin cited occurs this 

 statement : 



The methods employed by tlie different experi- 

 menters have been practically the same, so the 

 results should be comparable. 



Again, Professor Lipman points out the im- 

 portance of all investigators employing the 

 same brand, in fact the same lot, of dried 

 blood in comparative work, intimating that 

 the writer has ignored this point. This would 

 be an ideal condition, most certainly, the de- 

 sirability of which no one questions, but how 

 impractical! If investigators would submit 

 the analysis of such materials as the above 

 along with their reports, this would assist 

 greatly in comparative studies. The writer is 

 fully aware that dried blood may vary all the 

 way from 6 to 13 per cent, total nitrogen, and 

 had he not had clearly in mind the possible 

 influence of its composition on ammonifica- 

 tion, why should he have called the reader's 

 attention to this statement on page 23 of Bul- 

 letin 184? 



With the exception of the New Jersey figures, 

 the percentages given in Table No. 6 are based 

 upon blood meal containing 13.05 per cent, of 

 total nitrogen, and cottonseed meal with 7.84 per 

 cent, total nitrogen. In the New Jersey work, 

 Lipman (J. G.) states that the blood meal and 

 cottonseed meal contained, respectively, 13.18 per 

 cent, and 6.'' 05 per cent, total nitrogen. 



Unfortunately, the composition of the blood 

 meal employed by the different investigators 

 cited in the comparative studies, with one ex- 

 ception, was not given, and consequently the 

 writer, in order to get some basis for compari- 

 son, was compelled to compute the results 



