LINKEAIf SOCIETY OF LOXDOX. XIU 



theory. lu Ms time this homology of organs was determined solely 

 hy their similarity in position, development, structure, and other 

 characters, as observed in the plants compared ; in the present day 

 physiologists have to take into account the evidences, either of their 

 hereditary derivation from a corresponding organ in a common parent, 

 or of their being an early stage of development of organs which have 

 further progressed in plants to which their own race are supposed to 

 have given birth. It is in this respect chiefly that the arguments 

 put forth by Strasburger differ from those of his predecessors. Jiut 

 whilst giving him every credit for his patient and persevering elabo- 

 ration of details, we cannot but see in his derivative arguments mxTch 

 of purely imaginary mixed up with well-attested evidences. When 

 in the higher races of phaeuogamous plants we meet with staminodia, 

 carpidia, or other rudimentary or anomalous productions, we may 

 justly, with Darwin, conclude that they are the hereditarj'^ represen- 

 tatives of organs normally perfect in some parent race, but which, 

 in consequence of other adaptations of the general economy of the 

 plant, have, in the course of successive generations, become useless 

 and gradually reduced or almost obliterated, if not modified so as to 

 perform diff'erent functions. So when we find in a species, or group 

 of species, some one organ specially modified in adaptation to special 

 purposes, and thus difi^ering or progressing from the forms prevalent 

 in the genus or order to which it belongs, without retrogression in 

 other respects, and if we allow no fallacy to creep in as to what we 

 mean by progress or retrogression, we may perhaps conclude that we 

 have at the same time a specially modified race and unmodified de- 

 scendants of the race it has sprung from. But it is hard to believe 

 that Strasburger had any such solid foundations for his argument 

 that the envelope of the nucleus of Conifers is genetically the same 

 as the carpellary envelope of the higher Phgenogams. He does not, 

 as far as I can learn, pretend that this envelope is the reduced re- 

 presentative of organs more perfect in previous races ; for the pre- 

 sumed ancestors of Conifers are crj-ptogamic. He rests solely upon 

 the supposition that this envelope in Conifers is the first appearance 

 of an organ further developed in the outer integument of their de- 

 scendants, the Gnetaceae, and perfected in the carpels of their ulti- 

 mate progeny, the higher Dicotyledons. But there seems to be very 

 little beyond pure imagination upon which to foimd such a supposed 

 pedigree ; and many reasons present themselves against the belief that 

 the higher Dicotyledons can have descended from Gnetacese or 

 Gnetaceae from Conifers, or that Conifers ever produced any races 



