170 Descendenz und Hybriden. 



previous paper, see pages 308, 312, 328, 333 (of the same volume) ; 

 the account which follows deals chiefly with a few phenomena not 

 previously referred to. 



The result of the Grosses made with „Telegraph" and „Tele- 

 phone" was to confirm Mendel's account of the behaviour of the 

 cotyledon characters of peas on crossing. In the Grosses with 

 „Ringleader" the agreement with expectation was complete; in the 

 case of those with the small smooth yellow native pea (No. 1) a 

 Single absolute exception appeared in Fi, in which green appeared 

 instead of the expected yellow. In F> and Fs a few minor irregu- 

 larities were observed, also in respect of colour, which are probably 

 to be accounted for by imperfect ripening. In later generations the 

 behaviour of these characters was more regulär than in the earlier 

 ones, and this is perhaps to be associated partly with the better 

 health of the plants, but also, almost certainly, to an intensification 

 of the characters following upon the cross. Nevertheless, even in 

 Fl (plants), when the number of seeds born upon individual plants 

 was very small, totals closely approximating to Mendelian expectation 

 were obtained when the figures for several plants were combined. 



A summarized account of the Grosses between „French Sugar" 

 and No. 1 will be found on page 328 (example VI.). The colour 

 characters of the testa gave in Fi the proportion 9:3:4 already 

 observed by Tschermak in several instances, but not described 

 by him in terms of gametes. Other definite characters such as pre- 

 sence and absence of a parchment layer in the pod, follow Mendel's 

 law, although dominance is not perfect in this case; and certain 

 other less definite characters very probably behave in the same way. 



The cross between No. 2 and „Satisfaction", briefly described 

 on page 333 (example Vll), was only represented by a few indivi- 

 duals in the earlier generations, but on account of its peculiar inter- 

 est and because many of its offspring still survive for further 

 experiment, it is here described at considerable length. The colour 

 characters of the testa yielded in ¥■>, almost certainly, the proportion 

 27:9:9:3:16, observed by Tschermak in the case of certain 

 flower colours of Mattliiola; and an explanation of this proportion 

 is attempted on the same lines as in the previous instance. 



This cross seems also to afford an instance of remarkable inten- 

 sification of both the allelomorphic characters of the same pair, 

 namely tallness and dwarfness — the former in Fi, and both in Fa 

 and later generations. As regards shape of the seeds a compli- 

 cation is introduced by the appearance of the plant character, 

 dimpled seeds, in the offspring of a cross between parents which 

 showed the allelomorphic characters smooth and wrinkled cotyledons 

 respectively. 



A few other Grosses support Mendel's experiments and con- 

 clusions, which are indeed already sufficiently well established. 



R. H. Lock. 



Stone, WiTMER, Certain plant „Species" in their relation 

 to the Mutation theory. (Science. N. S. XXIII. p. 701^702. 

 May 4, 1906.) 



The acaulescent violet forms are regarded as not mutants but 

 perhaps „due to the action of immediate local environment, the 

 exact nature of which it is practically impossible for us to detect". 



Trelease. 



