From J. D. Hooker  June 18571
7. Brighton Terr. | Gt. Yarmouth
Saturday June 28/57.
Many thanks for the Embryonic Furze.2 The subject is one of great interest. A quite identical case is that of the Phyllodineous Acacias, which have pinnate leaves very early: & Eucalypti which have all opposite leaves when young—also many simple leaved Barberries have compound at very early state. A great stumbling block in developement to me has been the very great differences between the Cotyledonary leaves of plants—even of the same Nat. Order.—Leguminosæ for instance— this has always prevented me from understanding the embryonic developement in plants being so good an evidence of affinity as in animals. Comparative developement would appear to begin with the post Cotyledonary leaves, & the Cotyledonary may be regarded as placenta? Amnios? &c which vary? in allied animals. Is this not a shadow of a generalization?— I have often recommended germination & first formed leaves as the most interesting enquiry a young Botanist could take up, & particularly urged it upon G. Henslow—3 The latter two days ago sent me a letter that has given me great concern— he writes curtly to say that
Embryology of plants of low systematic order. Comparative development begins only with first post-cotyledonary leaves.
Curt letter to JDH from George Henslow.