540 LOTSY, CHARLES DARWIN OVER DEN INVLOED DER KRUISING. 
derden andere mogen intusschen te gronde zijn gegaan — onder 
de tegenwoordige omstandigheden belangrijk boven de andere be- 
voordeeld is; geschiedt dit wèl, dan wordt het Linneon overwe- 
gend eenvormig, zooals bij onze wilde konijnen. Zelfs zoo’n linneon 
is echter nooit volkomen homogeen, getuige bv. het voorkomen 
van kleine kolonie’s van zwarte en oranje-kleurige wilde konijnen 
in onze duinen. 
Het voorkomen van zulke kolonie’s is zeer interessant en moge- 
lijkerwijze een gevolg van voorliefde van bepaalde vormen voor 
elkaar, 
Hieromtrent zegt DARWIN: 
„Before giving the few recorded cases of forms, which must be 
ranked as varieties, being in some degree sterile when crossed, 
I may remark that other causes sometimes interfere with varieties 
freely intercrossing. Thus they may differ too greatly in size, as 
with some kinds of dogs and fowls: for instance the editor of the 
Journal of Horticulture, says that be can keep Bantams with 
the larger breeds without much danger of their crossing, but not 
with the smaller breeds, such as Games, Hamburgs etc. With 
plants a difference in the period of flowering seems to keep 
varieties distinct, as with the various kinds of maize and wheat; 
thus Colonel Le Couteur remarks „the Talavera wheat, from flo- 
wering much earlier than any other kind, is sure to continue pure” 1) 
In different parts of the Falkland Islands the cattle are breaking 
up into herds of different colours, and those on the higher ground, 
which are generally white, usually breed, as I am informed by 
Sir J. SULLIVAN, three months earlier than those on the low land; 
and this would manifestly tend to keep the herds from blending. 
Certain domestic races seem to prefer breeding with their own 
kind; and this is a fact of some importance, for it is a step. 
towards the instinctive feeling which helps to keep closely allied 
species in a state of nature distinct. We have now abundant 
evidence that, if it were not for this feeling, many more hybrids 
would be naturally produced than is the case. We have seen in. 
the first chapter that the alco dog of mexico dislikes dogs of other 
breeds; and the hairless dog of Paraguay mixes less readily with 

1) Dit voorbeeld is niet fraai, daar tarwe overwegend zelfbestuiver is. 
in FRE 
“aya 
ur ode pe 
PR MS 
