68 NA'lfHK OF DISCONTINUITY. [iNTROD. 



The best known instance of this that of gynandromorphic 

 in-e.-ts, in \\hi.-h the characters of the whole or part of one side 

 ..i the l""i\, \vm:,'> and antenna-, are male, while those of the 

 ,,t! e are female. 1 1 nmrkable instances of a similar pheno- 



menon have been recorded among bees and will be described later. 

 A- i- u. 11 known, the organs and especially the legs of the sex- 

 f. male* r workers are formed differently from those of the 

 dr.. ii.--. but there are cases of individuals having some of the 

 j.ari- and appendages formed on the one plan and some on the 

 other. Thus in these individuals, which are in a sense inter- 

 mediate between workers and drones, the characters of the two 

 mav still be not completely blended, the male type pre- 

 \ailiii:,' in .some parts, and the female in others. In the Dis- 

 continiiit v of Substantive Variation will be found examples of 

 imperfect blending of variety and type closely comparable with 

 tin- <-ase of the imperfect blending of Sex. 



SECTION XIII. 



Si GOES! K>NS AS TO THK NATUHE OF DISCONTINUITY IX VARIATION. 



'I'ln- ob-.-nations at the end of Section xi, regarding the Dis- 

 .-..iitinuity f M eristic Variation lead naturally to certain reflexions 

 .1- i.. i In- nature of Discontinuous Variation in general. In the 

 <>t' the < 'orkroaeh tarsus, there given, it appeared that just as 

 the -tnieture of the typical form varies about its mean condition, 

 BO the structure of the \arietv \ ai'ies about another mean condition. 

 Tlii- fa'-t. \\hieh in tin- gi\en instance of Meristic Variation is so 

 dear, at oiicc suggests an in.|iiiry whether this is not the usual 

 coin-.- of Discontinuous Variation, and, indeed, whether Discon- 

 tinuity in Variation docs not mean just this, that in varying the 



inism passes from a form \\hich is the normal for the type to 

 another form \\lii.-h i- a normal for the \ariety. Such transitions 

 plainly occur in many cases of McHst ic Variation, and in a consider- 

 able number of Sub-taut i\e Variations there will be found to be 

 indication- that the phenomenon is similar. It is true that at the 

 pn - nt stage of the in.|iiiry the .\ idence has the \alue rather of 

 'i"ii than of proof, but the suggestion is still very decided 

 and it i- scarcely poihle to exaggerate the importance of even 

 tin- slender clue. 



In stating the problem of Species at the ben-inning of this 

 inquiry it \\a- -aid that the forms of living things, as we know 

 them, constitute a di-continuou> series, and it is with the origin 

 "t tin- Discontinuity of the series that the solution of the main 

 pioKlrin is lar-.-K concerned. N.,\v tin- evidence of Discontinuous 

 \anation auggeets that organisms may vary abruptly from the 



