52 8 THE POPULAR SCIENCE MONTHLY 



especially on the butterflies and beetles, were gradually storing his mind 

 for one of those discharges of generalization which come so unexpectedly 

 out of the vast accumulation of facts. "The Malay Archipelago" of 

 1869, published seven years after the return, is Wallace's "journal of 

 researches," that is, it is to be compared with Darwin's great work of 

 this title. Its fine breadth of treatment in anthropology, zoologv', 

 botany and physiography gives it a rank second only to Darwin's 

 " Journal " in a class of works repeatedly enriched by British naturalists 

 from the time of Burchell's journey in Africa. 



Wallace's first trial at the evolution problem was his essay sent to 

 the Annals and Magazine of Natural History in 1855, entitled " On the 

 Law Which has Eegulated the Introduction of New Species." This 

 paper suggested the when and where of the occurrence of new forms, but 

 not the how. He concludes: 



It has now been shown, though most briefly and imperfectly, how the law 

 that "Every species has come into existence coincident both in time and space 

 with a preexisting closely allied species," connects together and renders intel- 

 ligible a vast number of independent and hitherto unexplained facts. 



In February, 1858, during a period of intermittent fever at Temate, 

 the hoio arose in his mind with the recollection of the " Essay " of 

 Malthus, and there flashed upon him all the possible effects of the 

 struggle for existence. Twenty years before the same idea, imder similar 

 circumstances, had come into the mind of Darwin. The parallel is 

 extraordinary as shown in the following citations : 



Darwin Wallace 



In October, 1838, that is, fifteen In February, 1858, I was suffering 



months after I had begun my syste- from a rather severe attack of inter- 



matic inquiry, I happened to read for mittent fever at Ternate, in the Moluc- 



amusement, "Maltiius on Population," cas; and one day, while lying on my 



and being well prepared to appreci- bed during the cold fit, wrapped in 



ate the struggle for existence which blankets, though the thermometer was 



everywhere goes on from long-con- at 88° Fahr., the problem again pre- 



tinued observations of the habits of sented itself to me, and something led 



animals and plants, it at once struck me to think of the "positive checks" 



me that under these circumstances described by Malthus in his "Essay 



favorable variations would tend to be '^n Population," a work I had read 



preserved, and unfavorable ones to be several years before, and which had 



destroyed. The result of this would he made a deep and permanent impres- 



the formation of netu species. Here, sion on my mind. These checks — war, 



then, I had at last got a theory by disease, famine and the like — must, it 



which to work; but I was so anxious occurred to me, act on animals as well 



to avoid prejudice that I determined as man. Then T thought of the enor- 



not for some time to write even the mously rapid multiplication of ani- 



briefpst sketch of it. In June, 1842, mals, causing these checks to be much 



I first allowed myself the satisfaction more effective in them than in the 



of writing a very brief abstract of my case of man; and while pondering 



theory in pencil, in thirty-five pages, vaguely on this fact there suddenly 



