sh o u ld n o t o n ly b e th e h ig h e s t n ow e x is tin g , b u t h a v e m o r e h ig h ly d iffe r en tia ted v e g e ta t iv e o rg an s
th a n a n y su b s e q u e n t ly ap p ea i'in g ; an d th a t th e d ic o ty le d o n o u s em b ry o an d p e r fe c t e x o g en o u s wood
w ith th e h ig h e s t sp e c ia liz ed tis s u e k n ow n {th e c o n ife r o u s , w ith g la n d u la r t is s u e * ) , sh o u ld h a v e p r e --
c e d ed th e m o n o c o ty le d o n o u s em b r y o an d e n d o g e n o u s w o od in d a te o f a p p ea ran c e o n th e g lo b e , are
fa c ts w h o lly op p o sed t o th e d o c tr in e o f p r o g r e ssio n , an d th e y ca n o n ly b e s e t a s id e o n th e su p p o sitio n
th a t th e y ar e fr a gm en ta r y e v id en c e o f a t im e fu r th e r r em o v ed from th a t o f th e o r ig in o f v e g e ta tio n
th a n from th e p r e sen t d a y ; to w h ic h m u s t b e added th e su p p o s itio n th a t ty p e s o f L y c o p o d ia c eæ , and
a n um b e r o f o th e r Ordei-s a n d G en e r a , a s low as th o s e n ow liv in g , e x is te d a t th a t t im e also.
A n o th e r p o in t is th e e r id e n c e ,f sa id to b e e s ta b lish ed , o f g en e r a n ow r e sp e c tiv e ly c o n sid e r ed p e c u lia
r t o th e fiv e c o n tin e n t s h a v in g e x is t e d c o tem p o r a n e o u sly a t a com p a r a tiv e ly r e c e n t g e o lo g ic a l ep o ch
in E u r o p e , an d th e v e r y c lo s e affin ity, i f n o t id e n tity , o f som e o f th e s e w ith e x is t in g sp e c ie s. T h e
c h a n g e s in th e le v e l an d c o n to u r o f th e d iffe r en t p a r ts o f th e ea r th ’s su r fa c e w h ic h h a v e occu rr ed
s in c e th e p e r io d o f th e ch a lk , or e v en s in c e th a t p r e c ed in g th e r is e o f th e A lp s , im p ly a v e r y g r e a t
am o u n t o f d iffe r en c e b e tw e e n th e p a s t an d p r e sen t r e la tio n s o f sea a n d la n d an d c lim a t e ; an d i t is
n o d o u b t ow in g t o th e s e c h a n g e s th a t th e A r a u c a r îoe , w h ic h o n c e in h a b ite d E n g la n d , are n o lo n g e r
fo u n d in th e n o r th e rn h em isp h e r e , an d th a t th e A u s tr a lia n g en e r a w h ic h in h a b ited E u r o p e at a p er iod
p r e c ed in g th e r is e o f t h e A lp s h a v e s in c e b e en ex p e lled .
S u c h fa c ts , s ta n d in g a t th e th r e sh o ld o f o u r k n ow le d g e o f v e g e ta b le p a læ o n to lo g y , sh o u ld lead
u s t o e x p e c t th a t th e p r o b lem o f d is tr ib u tio n is an in fin it e ly com p lic a ted o n e , an d su g g e s t th e id ea
th a t th e m u ta t io n s o f th e su r fa c e o f o u r p la iîe t, w h ic h r ep la c e c o n tin e n t s b y o c ean s, an d p la in s by
m o u n ta in s , m a y b e in s ig n ific a n t m e a su r e s o f t im e w h en com p a r ed w ith th e d u r a tio n o f s om e e x is tin g
g en e r a an d p e rh ap s sp e c ie s o f p la n ts , for s om e o f th e s e appear t o h a v e o u tliv e d th e slow su bm e rsion
o f c o n t in e n ts .
3 5 . P r om th e sum th e n o f o u r th e o r ie s , a s an*anged in a c co rd an c e w ith a sc e r ta in ed fa c ts, we
m a y m a k e th é fo llow in g a ssum p tio n s :— T h a t th e p r in c ip a l r e c o g n iz ed fam ilie s o f p la n t s w h ic h in h a b
it e d th e g lo b e a f a n d s in c e th e P a læ o z o ic pe r iod s t ill e x is t , an d th e r e fo r e h a v e a s fam ilie s su rv iv ed
a ll in t e r v e n in g g e o lo g ic a l ch a n g e s . T h a t o f th e s e ty p e s som e h a v e b e en tran sfe rr ed , or h a v e m ig r a ted ,
fr om o n e h em isp h e r e t o an o th e r . T h a t i t i s n o t u n r ea so n a b le to su p p o se th a t fu r th e r ev id en c e m a y
b e fo r th c om in g w h ic h w ill sh ow th a t a ll e x is t in g sp e c ie s m a y h a v e d e sc en d ed g e n e a lo g ic a lly from
few e r p r e -e x is t in g o n e s ; th a t w e ow e th e ir diffe r en t fo rm s to th e var ia tion o f in d iv id u a ls, an d th e
pow e r o f l im it in g th em in to g en e ra an d sp e c ie s to tb e d e s tru c tio n o f som e o f th e s e v a r ie tie s, e t c ., and
th e in c r e a s e in in d iv id u a ls o f o th e r s. L a s tly , th a t th e fa c t o f sp e c ie s b e in g w ith so m u c h u n ifo rm ity
th e u lt im a te a n d m o s t d efin ab le g rou p (th e le a v e s a s i t w e r e o f th e fam ily tr e e ) , m a y p o ss ib ly be
ow in g to th e t e n d e n c y t o va ry b e in g ch e ck ed , p a r tly b y th e am p le o p p o r tu n itie s e a ch b rood o f a
* The vexed question o f the true position of Gymnospennous plants in the Natural System assumes a somewhat
different aspect under the view o f species being created by progi-essive evolution. In the haste to press the
recent important discoveries in vegetable impregnation and embryogeny into tlie service o f classification, the long-
established facts regarding the development of the stem, flower, and reproductive organs themselves of Gym-
nospermous plants have been relatively unden-ated or wholly lost sight of ; and if an examination o f tlic doctrines
of pvogi'ession and variation lead to a better general estimation of the comparative value of the characters presented
by these organs, the acceptance or rejection of the doctrines themselves is, in the present state of science, a matter
of secondaiy importance.
t See first foot-note of p. x xi (*) : what I have there said of the supposed identifications of the Australian
genera applies to many of those of the other enumerated quarters of the globe.
v a r ie ty p o s s e s s e s o f b e in g fe r tiliz ed b y th e p o llen o f it s nca i’e.st c o u n te rp a r t, p a r tly b y th e tem p o ra ry
s ta b ility o f i t s su r r o u n d in g p h y s ic a l co n d itio n s , a n d p a r tly b y th e su p e rab u n d an c e o f se ed s sh ed b y
e a c h in d iv id u a l, th o s e o n ly v e g e ta tin g w h ich ar e w e ll su ite d to e x is t in g c o n d it io n s ; an ap p ea ran c e o f
s ta b ility is also, in th e c a se o f m a n y p e r en n ia ls, d u e to th e fa c t th a t th e in d iv id u a ls n o rm a lly a tta in a
g r e a t a g e ,* an d th u s su rv iv e m a n y g en e r a tio n s o f o th e r sp e c ie s, o f w h ich g e n e r a tio n s som e p r e s en t
ch a r a c te r s fo r e ign t o tlie ir p a r en ts.
3 6 . In th e ab o v e lin e o f a r g um en t I h a v e n o t a llu d ed to th e q u e s tio n o f th e o r ig in o f th o s e
fam ilie s o f p la n ts w h ich appear in th e e a r lie s t g e o lo g ic a l fo rm a tio n s , n o r t o th a t o f v e g e ta b le lif e
in th e a b stra c t, c o n c e iv in g th e s e t o b e su b je c ts u p o n w h ich , in th e p r e sen t s ta te o f s c ien c e , b o ta n y
th r ow s n o lig lr t w h a tev e r . R e g a rd ed from th e c la ssific a to r y p o in t o f v iew , th e g e o lo g ic a l h is to r y o f
p la n ts is n o t a lto g e th e r fa v ou rab le t o th e th e o r y o f p ro g r e ssiv e dcj’e lo pm en t, b o th b e ca u se th e e a r lie st
a s c e r ta in ed ty p e s are o f su ch h ig h an d com p le x o r g a n iz a t io n ,t an d b e c a u se th e r e a r e n o k n ow n fo s s il
p la n ts w h ich w e ca n c e r ta in ly a ssum e t o b e lo n g to a n o n -e x is tin g c la ss o r ev en fam ily , n o r th a t are
asc e r ta in ed to b e in te rm ed ia te in a ffin ity b e tw e en r e c en t c la sse s or fam ilie s. î
T h e pro g r e ss o f in v e s t ig a tio n m a y u lt im a te ly r e v e a l th e tr u e liis to r y o f th e u n r e c o g n iz ed v e g e ta
b le r em a in s w ith w h ich o u r c o lle c t io n s abou n d , an d m a y d isco v e r to u s anron g st th em n ew and
u n e x p e c te d o rg a n ism s, su g g e s tin g or p ro v in g a p ro g r e ssiv e d e v e lo pm en t ; b u t in th e m e a n t im e th e
fa c t r em a in s th a t th e p r om in en t p h en om en a o f v e g e ta b le p a læ o n to lo g y d o n o t ad v a n c e u s o n e s tep
tow a rd s a sa tisfa c to r y c o n c ep tio n o f tb e fir st o r ig in o f e x is t in g N a tu r a l O rd e rs o f p la n ts.
T a k in g th e C o n ife r s a s a n ex am p le , w h a tev e r ran k is g iv en to th em b y th e sy s tem a t is t , th a t th e y
sh o u ld h a v e p r e ced ed M o n o c o ty led o n s a n d m a n y D ic o ty le d o n s in d a te o f ap pearance o n th e glob e ,
is a fa c t q u it e in c om p a tib le w ith p ro g r e ssiv e d e v e lo pm en t in th e s c ie n tific a c c ep ta tio n o f th e te rm ,
w h ils t to a rg u e from th e ir a p p a r en tly ea r ly ap p earan c e th a t th e y are low in a c la ssifica to ry sy s t em is
b e g g in g th e q u e stio n .
A n o th e r fa c t t o b e b o rn e in m in d is , th a t w e h a v e n o ac cu ra te id e a o f w h a t s y s t em a t ic p r o g r e ss
io n is in b o ta n y . W e k n ow lit t le o f h ig h an d low in t lie V e g e ta b le K in g d om fu r th e r th a n is e x p
r e ssed b y th e s eq u en c e o f th e th r e e c la sse s. D ic o ty le d o n s , M o n o c o ty led o n s , aud A c o ty le d o n s ; an d
am o n g s t A c o ty le d o n s , o f T h a llo g e n s b e in g low e r th a n A c r o g eu s , an d o f th e s e th a t th e M o s s e s , e t c ., ai-e
low e r th a n F ilic e s a n d th e ir a llie s . I t is tr u e th a t we te c h n ic a lly co n s id e r m u ltip lic a tio n a n d c om p
le x ity o f floral w h o r ls in p hæ n o g am ic p la n ts as in d ic a tio n s o f su p e rior o r g a n iz a tio n ; b u t v e r y m a n y
* In eoiisidering the relative amount and rate at which different plants vary, it should be remembered that
we habitually estimate them not only loosely but falsely. We assume annuals to be more variable than perennials,
but we probably greatly o v em te the amount to wliich they really are so, because a brief personal experience enables
us to study many generations of an annual under many combinations of physical conditions ; whereas the same
experience embraces but a fractional period of the duration of (comparatively) very few perennials. It has also been
well shown by IBentham (in bis paper on the British Flora, read (1858) before tbe Linnæan Society) that an appearance
of stability is given to many varieties of perennials, thi'ough their habitual increase by buds, offsets, etc., which
pro])agate the individual ; and in the case of Rnbi, ivbich comparatively seldom propagate by seed, a large tract of
ground may be peopled by parts of a single indh'idual.
t I have elsewhere stated that I consider the evidence of A lg a having existed at a period preceding vascular
Ciyptogams to be of very little value. (Lond. Journ. Bot. viii. p. 254.)
t I t must not be supposed that in saying this I am even expressing a doubt as to there having been plants
intermediate in affinity between existing Orders aud Classes. Analogy witli the animal kingdom suggests that some
at any rate of the plants of the coal epoch do hold such a I'elationship ; but should they not do so, I consider this
fact to be of little value in the present inquiry, for I incline to believe that the ascertained geological history of
plants embraces a mere fraction of theii- whole history.