W. F. 1{. Wki.don 293 



(a) The numher of gametes of each kind is tlie saiiie ; this is of course a 

 Mendeliau hypothosis. 



{ß) The numher of «jcnni'tes, vinitiiiiniiij eleinents derived J'ruin tlw pureid iintk 

 simple cliaracter, in equal to the sam of (dl the otlier gametes, each of whicJi hau 

 a siiujle elenieid of tlie conipoimd parentül character. Here the view that gametes 

 of all kinds aiv produced in ci[ual iiuinhers is giveii up, in order to fit a particular 

 result. 



It is inipditant to notire tliat iieither of tho two hypotheses abovo describod 

 can be applied to any System of separable organs whose modifications are uiiited 

 to form a " Compound allelomorph," witliout involving the production of an 

 individual in which some of tlie characters are determined solely by that "residue" 

 from which all unit characters are abstracted, pictured by Mr Bateson as the 

 basis of our conception of Species. Yot he teils us that he has taken colour- 

 characters as examples of the way in which other cases may be treated, because 

 "the facts in thoso cases are clcarer, but thcir natiire is probably not different " 

 (II. p. 140). 



B. The Mendelian theorij, that all inherited characters are reduced to their 

 elemeutari/ uuits and redistributed during ganiete formation, is given up. 



Under this head we have two possibilities ; for some gametes of the hybrid 

 may contain the parental "compiuuid allclnmorph " either entire, or partly resiilved 

 into its constituents. 



The doctrines put forward by Mr Bateson in connection with " Compound 

 allelomorphisni " have been considered at some length, because of their great 

 interest to anyone who wishes to appreciate his attitude. It niust be remem- 

 bered that no character can, on Mendel's view, be asserted u priori to be simple or 

 Compound. If a simple result, such as that obtained by Mendel when he crossed 

 yellow and green peas, be obtained on crossing two animals or plants which diftc-r 

 in respect of any character, that character is simple, and there is no need to go 

 further. Should the hybrids e.xhibit any unexpected character, a refereuce to the 

 properties of "heterozygotes" will reuiove all difficulties ; should the offspring of 

 the hybrids be of more than two kinds, one or other of the foregoing hypotheses 

 will generally be found to evade the dithculty ; if not, "our conceptions of allelo- 

 morphic characters, simple and Compound, are in process of formation*," and a 

 new theory will (piickly be provided. 



We need not discuss the attenipt to regard the sex of ofTspring as a 

 phenomenon of gametic dittercutiation, a doctrine more difificult than even those 

 we have described, excepting only that of the marvellous residue without unit 

 characters, on which the future detinition of species must be based. We may now 

 proceed to examine the way in which Mr Bateson, after formulating all these 

 hypotheses, treats Mr Darbishire's new facts. 



* Bateson : " Note on the Kesolutiou of Compound Characters by Cross-breeding." Fruc. Cumbiiiliie 

 Phil. Soc. XII. p. 53. 



