522 CRITICAL PERIODS IN THE HISTORY OF THE EARTH. 



moon. In the latter it is sometimes called the hunter's moon. The full 

 moon occurring nearest to harvest time will always partake more or less of 

 the qualities of a full moon occurring at the autumnal equinox, and similarly 

 of a full moon following the autumnal equinox. So that, in almost every 

 year, there may be said to be a harvest moon and a hunter's moon. But, of 

 course, it will very often happen that in any particular agricultural district 

 the harvest has to be gathered in during the wrong half of the lunar month,, 

 that is, during the last and first, instead of the second and third quarters. 



The reader must not fall into the mistake of supposing, as 1 have seen 

 sometimes stated in text-books of Astronomy, that we are more favored ia 

 this respect than the inhabitants of the southern hemisphere. It is quite 

 true that the same full moon shines on us as on our friends in New Zealand,. 

 Australia, and Cape Colony, and also that our autumn is their spring, and 

 their spring our autumn. But the full moon we have in autumn behaves in 

 the southern hemisphere not as with us, but as our spring moon behaves j, 

 and the full moon of our spring, which is their autumn, behaves with them 

 as our autumn moon behaves with us. It is, therefore, for them a harvest 

 moon if it occur before the equinox, and a hunter's moon if it occur after 

 the equinox. A very little consideration will show why this is. In fact if, 

 in the explanation given above, the words north and south be interchanged^ 

 and March 21-22 written for September 22-23, the explanation will be pre- 

 cisely, that which I should have given respecting the harvest (or March) 

 moon of the southern hemisphere, if I had been writing for southern readers. 



GEOLOGY. 



On Critical Periods in the History of the Earth, and their Rela- 

 tion to Evolution; On the Quaternary as Such a Per'.od. 



BY JOSEPH LECONTE. 



[continued.] 



I have preferred, thus far, to speak of general evolution -changes of or- 

 ganisms, whether slow or rapid, as produced by varying pressure of exter- 

 nal conditions, and of the most striking local changes by migration from 

 other regions, where the apparently suddenly-appearing species had pre- 

 viously existed, having originated there by evolution in the usual way. I 

 have chosen, thus far, to represent the organic kingdom as lying, as it were- 

 passive and plastic under the molding hands of the environment. I have 

 done so because it is in accordance with true method to exhaust the more^ 

 obvious causes of evolution before appealing to the more abscure and doubt- 

 ful. 



