METHODS FOR PKOVING OEIGIN OF SPECIES. 15 



those of botanj if we would arrive at satisfactory con- 

 clusions. . 



3. Arohwology and PalcBontoiogy. The most direct 

 proof which can be conceived of the ancient existence 

 of a species in a given country is to see its recognizable 

 fragments in old buildings or deposits, of a more or less 

 certain date. 



The fruits, Seeds, and different portions of plants 

 taken from ancient Egyptian tombs, and the drawings 

 which surround them in the pyramids, have given rise 

 to most important researches, which I shall often have to 

 mention. Nevertheless, there is a possible source of error ; 

 the fraudulent introduction of modern plants into the 

 sarcophagi of the mummies. This was easily discovered 

 in the ease of some grains of maize, for instance, a plant' 

 of American origin, which were introduced by the Arabs ; 

 but species cultivated in Egypt within the last two or 

 three thousand years may have been added, which would 

 thus appear to have belonged to an earliier period. The 

 tumuli or mounds of North America, and the monuments 

 of the ancient Mexicans and Peruvians, have furnished 

 records about the plants cultivated in that part of the 

 world. Here we are concerned with an epoch subsequent 

 to the pyramids of Egypt. 



The deposits of the Swiss lake-dwellings have been 

 the subject of important treatises, among which that of 

 Heer, quoted just now, holds the first place. Similar 

 works have been published on the vegetable remains 

 found in other lakes or peat mosses of Switzerland, Savoy, 

 Germany, and Italy. I shall quote them with reference 

 to several species. Dr. Gross has been kind enough to 

 send me seeds and fruits taken from the lake-dwellings 

 'of Neuchitel; and my colleague. Professor Heer, has 

 favoured me with several facts collected at Zurich since 

 the publication of his work. I have already said that 

 the rubbish-heaps of the Scandinavian countries, called 

 kitchen'middens, have furnished no trace of cultivated 

 vegetables. 



The tufa of the south of France contains leaves and 

 other rfeinains of plants, which have been discovered by 



