326 Descendenz und Hybriden. 



clusions arrived at from the study of both kinds of plants were 

 summed up in a paper by these authors (Further Experiments with 

 Sweet Peas and Stocks: Preliminary Account. Proc. Roy. Soc. 1906.), 

 which was reprinted on p. 136 of the present volume of the Centralbiatt. 

 The present paper contains the evidence upon which the conclusions 

 there summarised were based. 



A „Chessboard" form of diagram is introduced which facilitates 

 the understanding of some of the more compHcated cases. Thus 

 when three pairs of allelomorphs are simultaneously considered, 

 eight different combinations of them occur in the gametes of the 

 hybrid in equal numbers; and the most probable result of the 

 random zygotic unions of these is set out in a diagram of 64 Squares. 



Turning to the section on Poultry: A different view of the 

 Malay comb is adopted to that of Report II. Two pairs of allelo- 

 morphs are now supposed to be concerned: Rose and no-rose 

 (R, no R); Pea and no-pea (P, no P). 



Malay is indicated by the simultaneous presence of R and of P. 



Rose is R no P. 



Pea is P no R. 



Single is no P no R. 



„We have already pointed out that the proportion of the different 

 combs in the various matings affords no criterion for judging be- 

 tween this view and the one previously suggested. The new view, 

 however, explains the identity of the combs produced by the cros- 

 sing of rose with pea and of r. p. with single, thus disposing of the 

 conceptions of Compound allelomorphs and synthesis". 



With regard to colour of plumage the existence of two kinds of 

 white birds was demonstrated. In one kind (D-whites) white is 

 dominant to colour, and in the other kind (R-whites) white is reces- 

 sive to colour. „These R-whites are characterised by the 

 possession of a few minute ticks in their other wise 

 pure white plumage." 



Every possible form of mating between Blue Andalusians 

 and the black and splashed white „wasters" was tested. The 

 figures given bear out the previous conclusion that blue is the 

 heterozygote form black X splashed white. R. H. Lock. 



Maiden, J. H., Further Notes on Hybridisation in the 

 Genus Eucalyptus. (Proceedings of the Linnean Society of New 

 South Wales for the year 1905. Vol. XXX. Part 4. No. 120. 

 1906. p. 492—501.) 



The author states the features, on which he relies in deternii- 

 ning a natural hybrid; they are: 1. occurrence in neighbourhood of 

 reputed parents and sparse distribution, 2. occurrence of reputed 

 hybrid, practically identical in character, in localities widely sepa- 

 rated, 3. simultaneous flowering of reputed parents and hybrid, 

 4. possession of intermediate characters. The chief hybrids dealt 

 with may be briefly summarised as follows : 



E. amygdalina X coriacea = E. vitellina Naudin and E. vi- 

 trea R. J. Baker; E. ohliqua X coriacea (?) = E. obliqua L'H^rit. 

 var. alpina Maiden (E. delegatensis R. J. Baker); E. trachyphloia 

 F. V. M. X Planclwniana G. v. M. = ? E. Baileyana F. v. M.; 

 E. piperita X Siberiana = ? £". Consideneana Maiden ; E. sidero- 

 phloia X hemiphloia = E. Boormani Deane and Maiden ; E. sidero- 

 xylon X inelliodora, not before described; E. sideroxylon X leuco- 



