PLAXTS IX IIEJ.ATIOX To MAX 35 



oo 



UGiits of liviug- urgaiii.Niiis i-cuiaiii I'ar Im'^uikI his pijwcrs of 

 yynthesis. 



The conditions under wldcli rial hit works in ilic vpffotablc 

 kingdom are the very (jpposite of all this. Starting fr«>ni 

 the ripened seed, consisting essentially of a single fertilised 

 cell and a surrounding mass of nutritive material, a root is 

 sent out into the soil and a shoot into the atmosphere, from 

 which the whole plant with all its tissues and vessels arc 

 formed, enabling it to rise up into the air so as to obtain 

 exposure to light, to lift up tons weight of material in the 

 form of limbs, branches, and foliage of forest trees, often to 

 a hundred feet or more above the surface, by means of forces 

 whose exact mode of operation is still a mysten.^ ; while by 

 means of the very same tissues and vessels those recondite 

 chemical processes are being carried on which result in the 

 infinitely varied products already very brietly referred to. 



The living plant not only builds up its own man-ellous 

 structure out of a few elements supplied to it either in a 

 gaseous or liquid state, but it also manufactures all the aj> 

 pliances — cells, vessels, fibres, etc. — needful for its complex 

 laboratory work in producing the innumerable l)V(v})roducts 

 possessing so many diverse properties useful to man, but which 

 were mostly unneeded by the remainder of the animal world. 



Usually botanists as well as zoologists are satisfied to de- 

 scribe the minute structure of the organs of j)lants or animals, 

 and to trace out as far as possible the changes that occur dur- 

 ing growth, without any reference to the unknown and un- 

 intelligible forces at work. As Weismann has state<l, the 

 fundamental question — ''the causes and mechanism by which 

 it comes about that they (the germicides or physinlogical 

 units) are always in the right place and develoj) into colls 

 at the right time" — is rarely or never touched uptju.' 

 Modern theories of heredity take for granted the essential 

 phenomena of life — nutrition, assiniilati(ui, antl growth. 



1 Tlie Germ riasiii, p. 4. 



