P OP ULAR MIS CELL AX Y. 



427 



caries until it has reached the pulp. The 

 inflammation of the pulp is particularly 

 violent and painful, because the tissue is so 

 richly provided with blood-vessels and nerve- 

 filaments. As the products of inflamma- 

 tion can not escape, they collect and work 

 their way downward, where they produce 

 the most painful inflammation of the roots 

 and the periosteum. The chief object of 

 the rational treatment of caries of the teeth 

 consists in the removal of every particle of 

 carious substance out of the diseased tooth 

 and the protection of the sound dentine 

 that has been exposed against external in- 

 jurious influences by covering it with a fine 

 substance which is not attacked by acids 

 gutta-percha, cement, or gold. Although 

 the dentine is not as unchangeable as en- 

 amel, but manifests, by becoming firmer or 

 softer, that it is not quite uninfluenced by 

 tissue-changes, yet its caries is not an irrita- 

 tive process that the dentine takes an active 

 part in, but a passive process, and conse- 

 quently the removal of all diseased portions 

 and the protection of the non-carious part 

 of the tooth suffices to stay the morbid pro 

 cess completely. 



Cooking by Steam. Professor Behrend, 

 of Hohenheim, has described his experi- 

 ments on the changes produced in the albu- 

 minoid matter of various seeds and of pota- 

 toes by steaming under high pressure. In 

 a preliminary experiment, the author found 

 that the albuminoids of lupine-seeds under- 

 went considerable decomposition by heating 

 with water under pressure, and that the de- 

 composition was greater as the duration of 

 the heating and the temperature increased. 

 Ee, therefore, set to work to investigate 

 whether the albumen was dissolved as well 

 as decomposed, and, if so, what the quan- 

 titative relations of these changes were in 

 various seeds, and more especially in the 

 raw starch material for the manufacture of 

 alcohol. Yellow lupines, peas, Hungarian 

 maize, dari (Sorghum tartaricum), and pota- 

 toes in separate lots, nine months dug and 

 just dug, were experimented upon. When 

 the determinations were made, the contents 

 of the flasks, especially when they were 

 very starchy, became viscid and tenacious, 

 like glue, at from 70 to 100 C, and at 

 130 C. they were almost clear, limpid 



liquids, with just a few flecks floating about, 

 while, as the heating was continued, the 

 masses became continually darker, the 

 brownness being more or less intense, ac- 

 cording as the substance was richer or poor- 

 er in nitrogen. It is hence inferred that 

 the brown coloration is the result of the 

 decomposition of nitrogenous substances. 

 In all cases an increase of the soluble nitro- 

 gen was observed, especially with lupines 

 and peas. The nitrogenous matter of maize 

 seems less soluble, and not so easily at- 

 tacked as that of lupines and peas. From 

 the fact that the chief difference observed, 

 after six hours of heating, was in the 

 amounts of the albuminoid dissolved, it 

 was inferred that the solution of albumi- 

 noids precedes decomposition, and this was 

 confirmed by subsequent experiment. 



Geographical Conditions and Civiliza- 

 tion. Mr. H. J. Mackinder shows, in a pa- 

 per on " The Scope and Methods of Geogra- 

 phy," how the distribution of men, their so- 

 cial and political relations, and the elements 

 of their civilization, are determined by fac- 

 tors of physical geography and of geology 

 back of it. " Each successive chapter post- 

 ulates what has gone before. The sequence 

 of argument is unbroken. From the posi- 

 tion of the obstacles and the course of the 

 winds may be deduced the distribution of 

 rain. From the form and distribution of 

 the wrinkle slopes and from the distribution 

 of the rainfall follows the distribution of 

 the drainage system. The distribution of 

 soils is mainly dependent on the rock-struct- 

 ure, and on a consideration of soil and cli- 

 mate follows the division of the world into 

 natural regions based on vegetation." Cer- 

 tain conditions of climate and soil are needed 

 for the aggregation of dense populations. 

 A certain density of population seems ne- 

 cessary to the development of civilization. 

 Again, comparatively undisturbed strata 

 usually underlie wide plains, and wide plains 

 seem specially favorable to the development 

 of homogeneous races, like the Russians and 

 the Chinese. Yet, again, the distribution of 

 animal, vegetable, and mineral products has 

 done much to determine the local character- 

 istics of civilization. An interesting chap- 

 ter of geography deals with the reaction of 

 man on nature. Man alters his environ- 



