GEOFFROY SAINT-HILAIRE ÉTIENNE (1772-1844) NATURALISTE.

autograph manuscript, On a preference of affinity ... in double monsters...; 27 folio pages in a sewn booklet of 7 bifoli. On double monsters and mated children. On a preference of affinity, a precociousness of welding, a more intimate bond, and greater relations of convenience in double monsters between certain analogous organs originating from each subject than with these organs and between these organs ordinarily united and subordinated in regular animals. Draft, with erasures, corrections and marginal additions, of a communication to the Royal Academy of Marseilles on "a fact of monstrosity", following observations of several "cases of double monsters or of coupled, welded children". It had been believed "that the elements of two subjects welded and believed to be engaged in each other had separately belonged to distinct germs. Convinced that we were dealing with two primitive units, two compositions that were at first distinct and regular, then brought together and disordered by a pathological affection, the explanations given [...] of the grafting of plants [...] were accepted intellectually with regard to the greatest animal complications. The monsters are not less than the regular animals subjected to a fixed rule, but in them, another rule, a new order and facts not less numerous and not less admirable in their learned complication, replace the rules, order and arrangement, of what judging according to our habits we call the normal state "... It is necessary to see what one calls the "monsters" as "precious sketches to consult". This is followed by a long study of the case of the pubiadelphia, or "case of two subjects united by the perineum", of which he saw a specimen in Montpellier...