January 31, 1913] 



SCIENCE 



177 



given on the basis of blood meal containing 

 13.05 per cent, total nitrogen, such as was em- 

 ployed by the Colorado Station. To the end of 

 making available more complete data for com- 

 parative studies, the writer would take this oc- 

 casion to urge those who are engaged in re- 

 search work to be less reluctant about giving 

 the details of their investigations, for it is ob- 

 vious that comparative work is impossible and 

 worthless except it be carried out with a strict 

 observance of points of technique. 



Professor Lipman refers to the importance 

 of having a large number of soils in any com- 

 parative study: 



It must also be added here that the comparison 

 of only a few soils can not be invested with much 

 importance, even if the soils are described by 

 similar names. 



In this matter, his point is well taken, but 

 when the data do not exist, we must be satis- 

 fied with the information at our disposal. 

 Moreover, it seems to the writer that a com- 

 parison of the ammonifying efficiency of 

 twenty-seven niter soils with that of ten soils 

 selected at random in Colorado and elsewhere 

 should have more weight than the critic would 

 concede. 

 Again, Professor Lipman writes: 



It is, of course, obvious that sandy loams may 

 embrace soils of very widely differing natures and 

 that no just comparison can be made between a 

 sandy loam, so called in one district, with a sandy 

 loam so called in another district. 



If this comment is intended as a criticism 

 of Bulletin 184, it is absolutely without foun- 

 dation, for no place in this publication can 

 there be found any statement which suggests, 

 implies or asserts a comparison of soils on a 

 physical basis. 



The one very important factor which the 

 writer is said to have given no consideration, 

 and upon which Professor Lipman has dwelt 

 at some length, is what appears to be a radical 

 departure from the normal in the method of 

 preparing the soil cultures for studying am- 

 monification. Professor Lipman states that 

 " Professor Sackett sterilizes his soils with 

 mercuric chloride and then rinses them with 

 sterile distilled water prior to inoculation with 



a soil infusion." Then follows a critical dis- 

 cussion of this method. 



The writer begs to state in defense of this 

 assertion that no such procedure has ever been 

 practised in his laboratory and probably never 

 will. This seemingly direct contradiction re- 

 solves itself into a rather amusing circum- 

 stance when it is learned that Professor Lip- 

 man has gained this erroneous impression, 

 upon which he has grounded his chief criti- 

 cism, from his failure to observe certain punc- 

 tuation marks in the crucial sentence. On 

 page 4 of Bulletin 184, this sentence occurs: 



As soon as the soils were air dry, which seldom 

 requires more than twenty-four hours in our atmos- 

 phere, each was ground in a glass mortar, steril- 

 ized with mercuric chloride and subsequently rinsed 

 with boiled, distilled water, and passed through a 

 thirty-mesh wire sieve. 



From this, it is perfectly clear to the writer 

 that it is the glass mortar which was sterilized 

 with mercuric chloride and subsequently 

 rinsed with boiled, distilled water. However, 

 Professor Lipman makes it the soil which re- 

 ceived this treatment, and thereby hangs the 

 tale. 



As confirming the Colorado investigations, 

 the writer is pleased to learn that on several 

 occasions Professor Lipman has noted a high 

 ammonifying efiiciency in soils of California, 

 which contain abnormal amounts of nitrate, 

 as well as in certain soils obtained from the 

 vicinity of Grand Junction, Colorado. 



Walter G. Sackett 



Laboratory of Bacteriology, 

 Colorado Experiment Station 



the terms segment and segmentation in 



GEOLOGY 



The terms segment and segmentation which 

 are so conveniently and widely used in the 

 biologic sciences have not found their way 

 into geologic literature to a very notable ex- 

 tent, although they seem to be well suited to 

 geologic science. In searching for a general 

 term which could be applied to a minor part 

 of the earth and having the dimensions of a 

 solid, the word segment appeared to me as the 

 most convenient, and on reflection I recalled 



