Notice of Dr. Hooker’s Flora of New Zealand. 245 
transported by natural causes now in operation. These are all ques- 
tions Hef to the diffusion and variation of. species, which will be 
dis ere and in the following s scan 
distribution. Comparative anatomy, which has thrown so great light 
upon this branch of. study in the sister kingdom, has not done so much * 
for asada er arises from several. causes: 1. The habits of allied 
plants do not differ so remarkably as those of animals, and there is con- 
sequently te modification of their functional organs. 2. The relation 
of these modifications to the habits and wants of ihe species, is in the 
animal kingdom directly appreciable, but in plants no such connection 
Can be traced.* 3. The individual organs of support, respiration, and 
reproduction, are infinitely more variable and susceptible of change and 
even pvemiian 4 in plants, without affecting the life either of the indi- 
vidual or of the species.t The result of these facts is that we have 
its and naam which we hav noe in the vegetable kingdom, and 
which the phenomena of Phaioac! assure us do not exist to a degree 
that has, within the limits of oh experience, ieee available for throw- 
ing much light on the subjec 
e — in favor of a permanence of specific characters in 
Plants 
, how 
ever much w e may a alter conditions ; it is much ore difficult t to pip tats 
an induced variety from reverting to its aad § state, though we perse- 
,. The structure of woods offers many illustrations of this, tee ireerire allied 
Plants (especially Leguminose) ditfering otively 3 in the nature, arra and de- 
ee cular and cellular tissues of their trun 
ted t 
ony known to be indicated ie ‘the structure, Nig the structure 
to the function. This is not so in the sister kingdom, for ie @ content 
esa al to he a climber, Boye Se sae 8 i ates are adapted to 
opt f that function e habit is not only indicated by the struc- 
ture but oes intr is explained by ihe ag ante eee | it en eae ve animal to ful 
t To take e an ex e of his ;—many plants ig ae a wild and culti- 
vated state, which sree ta abundantly by root or vision, white ae do not do so 
i. seed. acharis Alsinastrum is a conspicuous example: it is a unisexual wate 
of wick one sex alone was introduced omy North Segre into Tog la, 
Where it has within a few years so ad by division as to be a 5 ine men 
navigation, The dish i is another sale, it em Asi T beli ieve, saaee 
known to or even to bear pees. pi be still more remarkable case has 
been poi ed out to me by Mr. Brown, in t ph lant spread (not 
My cultiva er ~~ the whole oesk ¢ awe amie which  hente hermaphro- 
flowers, ery rarely seeds. 
T- 
