November 19, 1886.] 



scijsjsrcu. 



455 



view. That Gray's ' Manual ' is often used for the 

 mere determination of names of plants does not in- 

 terfere with this its higher and primary use. This 

 distinction ' A teacher ' seems to ignore. If he will 

 call to mind that it is not from finding out mere 

 names of objects, or giving them, but from weighing 

 and discussing the nature, meaning, and causes of 

 the relative affinities of organized beings, that the 

 whole philosophy of natural history has arisen, he 

 will perhaps agree that it is not best to teach pupils 

 to think that they have gained the least knowlege of 

 nature, when they merely know what their elders 

 name a given object. The name may be called a 

 necessary evil ; and unless, with it, is more emphati- 

 cally acquired a knowledge of the structural and 

 biological relations of the object which it bears to 

 other objects, it is worse than useless knowledge. 

 This idea should underlie every manual for instruc- 

 tion. Samuel H. Scudder. 



Coloring geological maps. 



Having occasion recently to have printed a minia- 

 ture geological map of Indiana, I endeavored to use 

 the colors recommended by the International congress 

 of geologists. Supposing that my endeavor might be 

 more or less suggestive to those interested in the sub- 

 ject, I sent specimens of the map to the members 

 present at the Berlin meeting of the congress, and 

 with them a letter in which I pointed out the diffi- 

 culties I had encountered in using these colors. I 

 am indebted to Dr. Persifor Frazer for calling atten- 

 tion to my oversight m using them. My apology is, 

 that I selected the colors from the specimen sheet 

 printed in Berlin, and sent out with the American 

 committee's report of the work of the congress. 

 This sheet is entitled the " Gamine des couleurs (pro- 

 visoire) pour la carte geologique Internationale de 

 r Europe." Upon it the colors for the Devonian are 

 for its three subdivisions, while no colors or modifi- 

 cations of colors are given for subdivisions of the 

 subcarboniferous, and no reference is made to ex- 

 planations elsewhere. On its face this sheet claims 

 to be complete in itself. 



Had I referred, as I see that I should have done, 

 now that Dr. Frazer calls my attention to the matter, 

 to the report of the international committee, and 

 then again to the proceedings of the congress, to 

 ascertain whether or not certain recommendations of 

 the committee were adopted, I should have found 

 that my difficulties had been anticipated, and should 

 have saved myself the trouble of mentioning them. 

 It seems to me, however, that the very fact that such 

 a process is necessary — that one cannot safely use this 

 color-scheme without explanations other than those 

 to be found upon the sheet — is evidence that this sys- 

 tem is not all that one might reasonably expect. 



As to the purpose of the scheme, I supposed from 

 the first that it was intended for geology the world 

 over; but, after my maps were partly printed, a 

 member of the American committee, to whom I 

 mentioned my difficulty, suggested that these colors 

 were intended only for European geology, and called 

 my attention to the title of the specimen sheet 

 given above. 



Dr. Frazer seems to think it unreasonable to ex- 

 pect any system of colors to give entire satisfaction 

 on so small a map. I have no fault to find with the 

 international system on this score, especially as the 

 geology of Indiana is very simple. 



The difficulty in subdividing the carboniferous does 

 not come from the scale of the map, but simply from 

 the absence of any fixed method of indicating the 

 subdivisions. To be sure, geologists are left to dif- 

 ferentiate as they choose, provided they all use 

 gray ; but I may use one method, and another per- 

 son may use a very different one, the result of which 

 is the absence of uniformity ; and uniformity, I take 

 it, is the prime object of a color scheme. In such 

 cases the subdivisions require explanations. My 

 idea of a universal color-system is, that, once intro- 

 duced, it would need no explanations. 



The report of the committee upon the map of 

 Europe suggests that in such a case as the one I 

 refer to in the letter sent out, when the terrane is of 

 a known system, but unknown subdivisions, an 

 initial letter be used in connection with the mean 

 shade of color. 



If, instead of colors, we are to use letters, I submit 

 whether we can fairly call such a method of repre- 

 sentation a color scheme. John C. Branner. 



Bloomington, Ind., Nov. 10. 



Butter and fats. 



Science (Sept. 10, p 223) says: "Dr. Thomas 

 Taylor's microscopic method for detecting the adul- 

 terations of butter with foreign fats seems destined 

 to assume as many shapes as Proteus." Were this 

 even so, it should not excite surprise, considering 

 that about sixty different compositions have been 

 secured under United States patents for ^butter sub- 

 stitutes, from which it will be seen that oleomarga- 

 rine has itself become a veritable ' Proteus.' Science 

 further says: " At first the globose forms obtained 

 by the boiling and subsequent slow cooling of butter, 

 and exhibiting the Saint Andrew's cross under polar- 

 ized lightj were brought prominently forward as dis- 

 tinguishing marks of pure butter." Answer : What 

 I have stated is, that, when pure butter is boiled, 

 cooled, and viewed as described, globose bodies (but- 

 ter crystals) appear, exhibiting the Saint Andrew's 

 cross, a fact not now disputed ; that lard similarly 

 treated yields a crystal, spinous, without cross ; that 

 beef-fat gives a branched and foliated crystal, with- 

 out cross, — all of which Professor Weber admits, 

 summing up the results of his first three experi- 

 ments in the following words : " Thus far the results 

 and statements of Dr. Taylor are fully corrobo- 

 rated." 



If, however. Science intends the inference that I 

 have represented that globose bodies with cross, dis- 

 covered in any butter-like material when boiled, is a 

 proof that said material is butter, I have only to say 

 that no such idea has ever been entertained by me, 

 or published over my signature. If the inference is 

 intended that the discovery of the butler crystal and 

 cross has some relation to my method of distinguish- 

 ing oleomargarine from butter, nothing could be 

 farther from the truth. My method of distinguish- 

 ing oleomargarine from butter consists simply in 

 demonstrating that certain forms of fatty crystals 

 not known to pure butter are constantly found in 

 oleomargarine ; and in order to accomplish this, I 

 examine the suspected material, as found in the 

 market, unboiled. By this means I can generally 

 detect at once the lard or other foreign fats, if the 

 material is an oleomargarine. It is manifest that the 

 Saint Andrew's cross found in pure butter would not 

 help me to discover crystals of lard in oleomargarine. 



