Prof. Owen’s Address before the British Association. 427 
. tial first step being due to the protoplasmic matter of a germ-cell and 
sperm-cell ; the former pre-existing in the form of a nucleus or proto- 
plast, the latter as a gra u In flowering plants it is conve 
rm 
the representative of a species undergves in a single individual, is called 
the “ metamorphosis.” But this term has practically been restricted to 
the instances in which the individual, during certain phases of the change, 
is free and active, as in the grub of the chaffer, or the tadpole of the 
the natives, and these egg-cases were covered b 
could have emerged without breaking through the case and the paint; but 
both were uninjured. In the egg-cases were discovered, Ist, a grub-like 
larvain the egg; 2d, a cocoon in the egg containing the unwinged, im- 
perfectly developed insect; 3d, the unwinged, imperfectly developed in- 
sect in the egg, free from the cocoon, and ready to emerge. 2: & 
ae : 
hension of that great kingdom of nature. This phase of botanical sci- 
ence gives the power of further and more profitable Lact such 
lar localities, The sum of these relations, forming ose phical dis- 
tributions of pl rests, perhaps at present necessarily, on an assump- 
viz: cheb eoek el 3 ated, or come into being, but 
; orbed. large tracts of dry land produce dry 
the heat they have absorbed. Thus large Saaues “eorores 
i eal distribution of 
plants, both directly and indirectly. It diffuses plants over a wider area 
of equal climate, on their productiveness, and en mits 
of their city to support different conditions. Agriculture 
Iso effects ‘modifications of climate. Certain species of plants re- 
