OTHER THEORIES OF SPECIES-FORMING. 357 



Mendel to the present. The bibliography in connection with this 

 paper is practically complete up to the date of its making. 



2 Correns. C. G., "Uber Levkoyen-Bastarde, zur Kenntniss der 

 Grenzen der Mendel'schen Regeln," Botan. Centralbl, LXXXIV, 



References to P- 97' I 9'> "Uber Bastarde zwischen Rassen von 

 recent work on Zea Mays," Ber. Dent. Bot. Ges., XIX, 211 (1901); 

 Mendelism, "Bastarde zwischen Maisrassen, Bibliotheca Bota- 



nica," Heft 53, 1901 ; "Uber Bastardirungs-Versuche mit Mirabilis- 

 Sippen," Ber. Deut. Bot. Ges., XX, 594-608, 1903. 



3 T. E. Tschermak, "Uber kiinstliche Kreuzung bei Pisum sati- 

 vtim," Zeitschr. f. d. Landwirthsch. Versuchswescn, III, 465-555, 

 1900 ; "Weitere Beitrage iiber Verschiedenswerthigkeit der 

 Merkmale bei Kreuzung von Erbsen und Bohnen," ibid. IV, 641 ff., 

 1901 ; "Uber Ziichtung neuer Getreiderassen mittelst kiinstlicher 

 Kreuzung," ibid. IV, 1902. "Die Theorie der Kryptomerie und des 

 Kryptohybridismus," Beihefte s. Bot. Centralbl.,, XVI, 25 pp., 1903; 

 ''Weitere Kreuzungsstudien an Erbsen," Zcitschrift f. d. Landii'irth- 

 Versuchswesen in Oesterr., 106 pp., 1904. 



4 See Darwin, "Animals and Plants Under Domestication," Vol. 

 I, chap, iii, p. 104. "In some few instances new breeds [of sheep] 



Darwin on have suddenly originated; thus in 1791 a ram-lamb was 

 race origin from born in Massachusetts, having short crooked legs and 

 sports, a long back, like a turnspit dog. From this one lamb 



the otter, or ancon, a semi-monstrous breed, was raised; as these 

 sheep could not leap over the fences it was thought that they would 

 be valuable ; but they have been supplanted by merinos, and thus 

 exterminated. The sheep are remarkable from transmitting their 

 character so truly that Colonel Humphreys never heard of 'but one 

 questionable case' of an ancon ram and ewe not producing ancon 

 offspring. When they are crossed with other breeds the offspring, 

 with rare exceptions, instead of being intermediate in character, 

 perfectly resemble either parent ; even one of twins has resembled 

 one parent and the second the other. Lastly, 'the ancons have been 

 observed to keep together, separating themselves from the rest of 

 the flock when put into enclosures with other sheep.' 



"A more interesting case has been recorded in the Report of 

 the Juries for the Great Exhibition (1851), namely, the produc- 

 tion of a merino ram-lamb on the Mauchamp farm, in 1828, which 

 was remarkable for its long, smooth, straight, and silky wool. By 

 the year 1833 M. Graux had raised rams enough to serve his whole 

 flock, and after a few more years he was able to sell stock of his 

 new breed. So peculiar and valuable is the wool, that it sells at 

 25 per cent, above the best merino wool : even the fleeces of half- 

 bred animals are valuable, and are known in France as the 



