56 



MORPHOLOGY. OF SPERM ATOPHYTES 



phylloclads themselves only gradually acquire their peculiar 

 character (Fig. 42, E, F). The juvenile forms of Sciadopitys, 

 like those of Pinus, show simple needle leaves upon long shoots, 

 but later scales occur instead of needles, and in their axils the 

 peculiar double needle leaves are developed. 



Goebel suggests that the juvenile forms probably represent 

 the more primitive form. These facts in connection with the 



FIG. 41. Sciadopitys verticillata : at the left an ovulate strobilus, at the right a branch 

 with staminate strobili, one third natural size (from Gardener's Chronicle) ; a, ven- 

 tral view, and ft, dorsal view of staminate sporophyll ; c, ovulate sporophyll ; d, cross 

 section of the double leaf: a, 6, c, after Sieb. and Zucc. Whole figure from ENG- 

 LER and PRANTL'S Nat. Pflanzenfam. 



group furnish an admirable illustration of what the zoologists 

 have styled the " recapitulation theory," which has been tersely 

 defined as meaning that ontogeny repeats phylogeny. It is cer- 

 tainly true that if the adult bodies of many of the forms not 

 mentioned above be associated with these juvenile forms, a 

 very consistent shoot body is discovered for Conifers. It would 

 follow that the replacement of foliage leaves by scales on the 

 long shoots of Pinus, Sciadopitys, and Phyllodadus ; the pecul- 



