Yoursverysincerely，C。DARWIN。
P。S。——HereafterIshallbeparticularlycurioustohearwhatyouthinkofmyexplanationofEmbryologicalsimilarity。OnclassificationIfearweshallsplit。DidyouperceivetheargumentumadhominemHuxleyaboutkangarooandbear？
ERASMUSDARWIN（Hisbrother。）TOCHARLESDARWIN。
November23rd[1859]。
DearCharles，Iamsomuchweakerinthehead，thatIhardlyknowifIcanwrite，butatalleventsIwilljotdownafewthingsthattheDr。（Dr。，afterwardsSirHenryHolland。）hassaid。Hehasnotreadmuchabovehalf，soashesayshecangivenodefiniteconclusion，anditismyprivatebeliefhewishestoremaininthatstate……Heisevidentlyinadreadfulstateofindecision，andkeepsstatingthatheisnottieddowntoeitherview，andthathehasalwaysleftanescapebythewayhehasspokenofvarieties。I