5o6 



THE POPULAR SCIENCE MONTHLY. 



cially of Montana, Wyoming, and British Amer- 

 ica. Prof. Cyrus Thomas, who has had an ex- 

 cellent opportunity of studying it through his 

 connection with Hayden's geological survey of 

 the Territories reports it ae occurring from 

 Texas to British America, and from the Missis- 

 sippi (more correctly speaking, the line I have 

 indicated) westward to the Sierra Nevada range. 

 But in all this vast extent of country, and es- 

 pecially in the moe southern latitudes, there is 

 every reason to believe that it breeds only on 

 the higher mountain elevations, where the at- 

 mosphere is very dry and attenuated, and the 

 soil seldom, if ever, gets soaked with moist- 

 ure. . . 



"My own belief is, that the insect is at home 

 in the greater altitudes of Utah, Idaho, Colorado, 

 Wyoming, Montana, Northwest Dakota, and 

 British America. It breeds in all this region, 

 but particularly on the vast hot and dry plains 

 and plateaus of the last-named Territories, and 

 on the plains west of the mountains; its range 

 being bounded, perhaps, on the east by that of 

 the buflalo-grass. 



"In all this immense stretch of country, as 

 is well known, there are vast tracts of bar- 

 ren, almost desert land, while other tracts, for 

 hundreds of miles, bear only a scanty ve;i:eta- 

 tion, the short butlalo-grass nf the more fertile 

 prairies giving way, now to a more luxurious 

 vegetation along the water-courses, now to the 

 sage-bush and a few cacti. Another physical 

 peculiarity is found in the fact that while the 

 spring on these immense plains often opens 

 as early, even away up into British America, 

 as it does with us in the latitude of St. Louis, 

 yet the vegetation is often dried and actually 

 burned out before the first of July, so that 

 not a green thing is to be found. Our Rocky 

 Mountain locust, therefore, hatching out in un- 

 told myriads in the hot sandy plains, five or six 

 thousand feet above the sea-level, will often per- 

 ish in immense numbers if the scant vegetation 

 of its native home dries up before it acquires 

 vvings ; but if the season is propitious, and the 

 insect becomes fledged before its food-supply is 

 exhausted, the newly-acquired wings prove its 

 Balvation. . . Prompted by that most exi- 

 gent law of hunger spurred on for very life it 

 rises in immense clouds in the air to seek for 

 fresh pastures where it may stay its ravenous 

 appetite. Borne along by the prevailing winds 

 that sweep over these immense treeless plains 

 from the northwest, often at the rate of fifty or 

 sixty miles an hour, the darkening locust-clouds 

 are soon carried into the more moist and fertile 

 country to the southeast, where, with sharpened 

 appetites, they fall upon the crops like a plague 

 and a blight. . . . The hotter and drier the sea- 

 son, and the greater the extent of the drought, 

 the earlier will they be prompted to migrate, 

 and the farther will they push on to the east 

 and south. 



" The comparatively sudden change from the 

 attenuated and dry atmosphere of five to eight 

 thousand feet or more above the sea-level to 

 the more humid and dense atmosphere of one 



thousand feet above that level, does not agree 

 with them. The first generation hatched in this 

 low country is unhealthy, and the few that at- 

 tain maturity do not breed, but become intestate 

 and ' go to the dogs.' At least, such is the case 

 in ourown State, and in the whole of theMissis- 

 eippi Valley proper. . . ." 



Temper.itnie and Vegetation in Diflferent 

 Latitndes. A communication on this sub- 

 ject was made by M. Alphonse de Candolle 

 to the Academy of Sciences of Paris, and re- 

 ported in the Comptes Rendus for June ^th. 

 The object of the inquiry was to test the 

 accuracy of the very common observation 

 that vegetation comes forward much more 

 rapidly in spring in northern latitudes than 

 in the warmer regions of the temperate 

 zone. Experimenting with seeds of several 

 species of plants sent to him from Northern 

 and Southern Europe, he found that those 

 from the north were most precocious. 

 Twigs, obtained in the winter, of the white 

 poplar, tulip-tree, catalpa, and the Carpinus 

 betulus, from Montpellier, were there tried 

 with twigs from the same species at Geneva. 

 They were laid aside, so that their tempera- 

 ture might become alike, and were then 

 placed in water, a little sand being put in 

 the bottom of the jar. 



The German, or more northern branches, 

 leafed out first ; the difference of time be- 

 tween the leafing of the respective pairs 

 being from eighteen to twenty-three days. 



It is an interesting question, " Why do 

 northern plants develop more rapidly than 

 southern ones ? " Prof, de Candolle com- 

 ments on it in this wise : " The buds of a 

 tree are in a continual struggle. The later, 

 like badly-placed ones, develop imperfect 

 branches which are oftener stifled. The 

 most precocious prevail, unless indeed they 

 suffer from frost. In this way comes a 

 selection, and a successive adaptation of 

 the tree to the climate." 



Buds, by this means, acquire peculiari- 

 ties which are persistent. If there be 

 promptness and quickness of growth, these 

 qualities are continually reproduced. An 

 instance of the persistency of acquired pe- 

 culiarities is given in a horse-chestnut tree 

 near Geneva, which, on a single branch, 

 produced double flowers about the year 

 1822, and has continued to do so; and all 

 the doubled-flowered horse-chestnuts in the 



