n6 PLANT PHYSIOLOGY 



11. 47-51, delete All stages . . . cells concerned. 



I. 55, for similar stimulus, read stimulus in this connexion 



371, 11. 3-12, delete Bearing on ... non-nucleate egg. 



372, 11. 10-14, for If we now . . . studied, read Fertilization need not, how- 

 ever, have everywhere the same significance. It must have a special and 

 abnormal purpose in cases like the Diatomaceae, which consist of two half 

 shells, and which at every successive division must necessarily become smaller 

 and smaller. In this case the enlargement of the cell is the immediate result 

 of conjugation. 



If we now desire to investigate more closely the complete fusion of pri- 

 mordia in fertilization we find ourselves face to face with the problem of the 

 ' physiology of heredity ' ; we have to inquire what characteristics of the 

 father and what of the mother reproduce themselves in the offspring, and in 

 order to study the subject it is necessary to cross two individuals which exhibit 

 marked differences. 



II. 26-7, for for read from ; for Among botanists ... to conduct read 

 LINNAEUS was the first to raise a hybrid between Tragopogon pratensis 5 and 

 T. porrifolius a* , while later on KOLREUTER (1761) conducted 



11. 32-6, for purposes ; . . . 1905]). read purposes. The nature of the laws 

 which govern hybridization did not appear in FOCKE'S general summary of 

 observations on the subject, published in 1881. These laws were first 

 discovered when, following MENDEL (1866-70), one began to investigate 

 statistically the whole preliminary history of a hybrid. MENDEL'S numerous 

 experiments which had almost been forgotten were brought to light again 

 in i goo almost simultaneously by DE VRIES, CORRENS, and TSCHERMAK, and 

 the principal results of these experiments have been clearly enunciated by 

 these authors. In the six years which have elapsed since then, numerous 

 investigations have been made which have been several times summarized 

 (CORRENS, 1901 a, 1903, 1905 b ; DE VRIES, 1903 ; BATESON, 1907). A new 

 branch of science has sprung into being, common to Zoology and Botany. 

 In order to gain some acquaintance with its results it will be possible for us 

 to mention only a few facts, and these we may take especially from the treatise 

 published by CORRENS (1903 b). 



I. 49 P. 373, 1. 3, for It is usually . . . may be induced, read The pollen- 

 tubes find on the stigma a chemical substratum which as yet has been in- 

 sufficiently investigated, and which we as yet have been unable to imitate 

 artificially ; but we may say with certainty that the germination of the pollen- 

 grains is determined by the conditions obtaining on the special kind of stigma 

 in question. The pollen-tubes of Mirabilis longiftora are perfectly adapted 

 for germination on the stigma of M. Jalapa, but the converse is not the case 

 (comp. JOST, 1907). 



II. 11-46, for No general rule . . . show variations, read If two breeds, 

 which differ in one point only, be crossed, one would think the hybrid must 

 be intermediate in this character between its parents ; but this is by no means 

 the rule. When MENDEL crossed a white-flowered with a red-flowered pea 

 the hybrid was not pink but red. As we have already seen, however, white 

 initials are not obliterated but are only inhibited from appearing by the red, 

 hence MENDEL spoke of the red as dominant and the white as recessive. 

 Although the domination of one initial over another is so frequent that one 

 may speak of it as the 'rule of prevalency ', still it is not so general as one at 

 first thought (CORRENS, 1903). We know of cases in which the one initial 

 inhibits the other only to a certain extent without actually suppressing it, 

 and we know of hybrids where both initials are equally active, so that forms 



