2o6 



SCIENCE. 



can hogs, the fact will be demonstrated; if, on the con- 

 trary, Trichinae are found, the extent of the trouble will 

 be known and steps can be taken to protect the in- 

 dustry by systematic examination. We believe that 

 the presence of Trichina; in pigs is confined to certain 

 districts ; if so, it can be localized, and the work of 

 investigation gradually reduced within certain limits, 

 and eventually, by proper precautions, the evil would be 

 entirely removed. 



MOUNTAIN ELEVATION, AND CHANGES OF 

 TEMPERATURE, IN GEOLOGY. 



By Samuel J. Wallace. 



It seems a very little thing for heat and cold to play 

 over the face of a continent. But light and unnoticed 

 as the creeping of fate it goes on forever ; and the foun- 

 dations of the everlasting hills are in its iron grasp. 

 Cold and heat. What should a rock-ribbed continent 

 care for them ? What do they do? 



In latitude 40° to 50° a yearly change of ten degrees 

 of heat penetrates the upper strata to considerable 

 depths ; and the expansion of various kinds of stone for 

 io 9 varies from one to three feet in twelve thousand ; 

 making, say, one foot to the mile, which across North 

 America is half a mile. 



This is an always recurring and resistless force of out- 

 ward thrust. It is probably mostly compensated for in 

 its habitual recurrence by elasticity, slippages of strata 

 on others, and by fissures ; as well as by the fact that 

 the expansion of solid strata is sometimes less from the 

 deep drift or soil protecting them. But, still, as the su- 

 perior force is outward, without anything to compel a 

 full return in winter, and as the expansion is less below 

 and greater above, the continued tendency is to push the 

 upper strata forward over others toward the margins of 

 extended plains, with a creeping motion, tending to force 

 up bendings, folds and faults, and to raise mountains and 

 plateaus slowly ; and even to accumulate such strain or 

 tension as to cause earthquakes and volcanos. 



Though, as Dana and others think, there has been a 

 singular persistence in the general features of deep 

 oceans and of continental tables, yet, great portions of 

 the tabular areas have had their depressions and up- 

 heavals from the sea. What must have occurred in 

 such cases? 



If a tract of sea-bed is covered by an arctic current at 

 32 , the cold must finally penetrate to A ery great depths. 

 Then, should the polar current by any means be shut off, 

 and a warm current flow over it, the temperature would 

 certainly be raised several degrees, and produce an ex- 

 pansion which would find relief in raising mountain 

 ridges, or in arching up its own or other regions. This 

 might go on slowly till great areas were elevated from 

 the ocean. 



Rising from the sea, also, would increase the tempera- 

 ture very much, to heave up mountains and plateaus, or 

 still other lands from the sea. This result it seems would 

 have to occur, because of the great depths to which the 

 expansion would reach, and because there would exist no ! 

 provision for relief of the tension, such as the repeated 

 yearly expansion would work out for itself. 



It seems these results must flow from what we already 

 know, whether there is or not, any other cause of eleva- 

 tion. There are some further considerations that may be 

 noticed here. 



Where a deep ocean trough bearing an arctic current 

 lies along beside a continent it would form a fixed barrier 

 to such expansions, and probably a chain of mountains 

 would be forced up along it, together with volcanos and 



earthquakes. The region of least yearly change and great- 

 est cold is said to be in the northern edges of America and 

 Siberia, and the bar connecting them across the pole. 

 From the ends of this region the annual change increases 

 southward and laterally. Singularly, the principal moun- 

 tain systems of the northern hemisphere seem as if raised 

 by forces or thrusts radiating from this bar and its ends. 

 In America, as Dana shows, the original core of the conti- 

 nent was V-shaped, with its two ridges facing the end of 

 that cold bar between them. And the later elevations 

 preserve parallelism to these original lines, as if showing 

 thrusts from that bar and from each other. In Europasia 

 occur continuations of the same parallelism of elevations 

 as facing thrusts radiating from the sides and the other 

 and broader end of the same cold bar, to the areas of 

 greatest annual changes southward, with still increased 

 force and complexity. 



In the southern hemisphere the bases of thrust seem as 

 if, on the contrary, they were the three great ocean beds. 

 And the great mountain systems of the world seem as if 

 raised by thrusts of force radiating from these great 

 northern and southern centers of land and ocean, oppos- 

 ing each other, together with some cross thrusts over 

 broad areas of land. This feature of opposition between 

 the northern land thrusts and the southern ocean beds, 

 brings some of the principal lines of elevation in the 

 northern hemisphere into diagonal courses, except where 

 sweeping around the northern projections of the oceans, 

 especially that of the Indian ocean, and its former con- 

 nection west to the Atlantic south of Europe. 



The present Alleghany system seems to have been 

 raised by the elevation of the Mississippi Valley from the 

 sea during and after the Carboniferous period ; the Rocky 

 Mountains by that of the plains, later ; and the Alps by 

 that of Northern Africa and Northern Europe, although 

 previous elevations existed. 



The familiar example of ice creeping up the shores of 

 ponds and lakes, from repeated changes of temperature 

 in winter, illustrates the principle of such elevations, the 

 walled lakes of Iowa being special illustrations ; and in- 

 teresting observations have been published, showing from 

 fixed levels that oscillations of level do occur from changes 

 of temperature. 



REMARKS ON A PATHOGENIC SCHIZOPHYTE* 



Prof. H. J. Detmers. 



When about two and a half years ago it became my 

 duty to investigate the prevailing Swine-plague, the so- 

 called Hog-cholera, I first endeavored to ascertain the na- 

 ture and the cause of that disease, and to accomplish my 

 object, made numerous post-mortem examinations, and 

 paid special attention to the microscopic examinations of 

 the blood and of the morbid products and morbid tissues. 

 Although the microscope at my disposal at the beginning 

 of my investigation is only a small No. VIII Hartnack 

 stand with three Hartnack and Prazmowski objectives — a 1 

 inch, a % inch, and a 1 -9th inch imm. and correctives — 

 and consequently not a strictly first-class instrument, and 

 in its performance by no means equal to the work of a 

 : Tolles or a Zeiss, I soon became convinced that the blood, 

 the morbid products, and the morbid tissues of the dis- 

 eased and dead animal invariably contained, while fresh, 

 and not tainted by putrefaction, a certain kind of Schizo- 

 ' phytes or bacteria. The same presented themselves in 

 three different shapes, namely as small globular bacteria 

 or Micrococci, as Zoogloea-masses or clusters, imbedded in, 

 or kept together by, a viscous mass, and as little rods or 

 filaments. I soon found that all three forms belong to the 

 same organism, and represent only different stages of de- 

 velopment. The first or globular form predominated in 

 the blood, the second in the morbid tissues— for instance, 

 in the diseased portions of the lungs and in the lymphatic 



* Read before the State Microscopical Society, of Illinois, April 8th, 

 1881. 



