9(5 PKOF. W. GARSTANG ON THE THEOKY OF RKCAPITULATION : 
elaboration of pre-existing structures (arms, stem-ossicles). Nature does 
not build up a new type by addition or abstraction of " stages," but of 
organs, or parts of organs *. Moreover, when she makes a change, she does 
not do so by altering these organs, or parts of organs, when fixed or rigid, 
but when plastic and growing. In particular cases this may be late in life, 
but it is not usually so, and it is not likely to have been so with respect to 
the patinal skeleton of the Grinoids under consideration. The Anal plate 
within the circlet of Radials is a feature inherited from earliest Silurian 
ancestors. It is claimed to "recapitulate" an adult feature of those 
ancestors. I submit that no Anal or other plate was ever interpolated within 
the patina except in the formative stage of growth when the Radials them- 
selves were loose and unsutured. The first Anal plate that entered the 
Radial circlet from the disk (if that was its origin) must have done so as the 
result of an embryonic, not an adult, mutation. Once let the towering anal 
chimney of an adult Dendrocrinoid {cf. Bather's fig. iii.) efi'ect a breach in 
the wall of the patina, and* the whole cup would split asunder. Nature 
underpins when it is safe to do so. She usually builds the foundation first 
and the superstructure afterwards. 
16. The following summary, omitting illustrative detail, recapitulates in 
closer logical sequence the chief points of this attempt to re-define the 
foundations of Morphogenetic Law. 
Recapitulation. 
I. Ontogeny is the sequential expression of yygotic powers of cell-division 
through simple to complex grades of cell-grouping and difif'eren- 
tiatiou. 
II. Phylogeny is the procession of ontogenies along a given phj'letic line 
of modification. It is expressed in terms of adult structure, but 
the zj'gotes of successive ontogenies have also undergone a parallel 
elaboration of nuclear or cytoplasmic structure, or of both, which 
determines the sequence of the ontogenetic form-changes. 
III. The phyletic succession of adults is the product of successive onto- 
genies. Ontogeny does not recapitulate Phylogeny : it creates it. 
IV. An individual confronts the world before his ontogenetic processes 
are completed, and often at a very early period of his life-cycle. 
Only those individuals reproduce who have survived the ordeal of 
larval conditions. Adaptation of the larva accordingly plaj's a 
prime part in determining the modification of successive ontogenies. 
* Cf. Weisniaiin (1904, ii. p. 174) : ". ... it is impossible to compare a particular stage 
in the embryogenesis of a species witb a particular ancestral form. Only the stages of 
individtial organs can be thus compared and parallelized." 
