1218 Growth, its Conditions and Variations. [December, 
We cannot undertake here to consider the various huge crea- 
tures which successively appeared and vanished, with the proba- 
ble cause of their success. It is simply our purpose to generally 
illustrate the principles of growth already reviewed. A brief 
reference to the vegetable kingdom, however, is here of some 
importance. In this kingdom nutriment is not consumed in pro- 
ducing muscular, nervous or temperature vigor, and reproductive 
energy alone competes with growth vigor. In vegetables, as in 
animals, those that employ most nutriment in reproduction attain 
the least size. The trees which bear juicy fruits, and which thus 
lay up a large stock of protoplasm for the use of their offspring, 
are smaller and shorter lived than the nut-bearing, and these 
again than the seed-bearing. 
Also in vegetables as in animals the size is greatly affected by 
the degree of efficiency in food-taking, and by the character of 
the embryological development. The spore-bearing plants, the 
ferns, mosses, &c., yield cases of larval birth. The young 
needs to pass through a phase of metamorphosis which con- 
sumes much of its initial growth energy. Other facts in this 
connection are the following: Plants which are prevented from 
_ seeding are longer lived and grow to greater bulk. On the con- 
trary, those which flower early die young, and the cultivation of 
fruit trees for early and extreme bearing shortens their lives. 
Again, plants of imperfect organization often attain great size 
in situations of high temperature, abundant nutrition and de- 
creased reproduction. Such is the case with the tree ferns of the 
tropics, and such was the case with the many huge plant forms 
of low organization in the Carboniferous age of geology: 
this respect plants present phenomena somewhat parallel with 
those of animal life. With the appearance of the exogens ae 
gan a retreat of the endogens and the lower forms. While 
palms, ferns and other low forms have been able to hold their ow" 
in the tropics, the exogenous trees have gained the supremacy 
in colder climates. In these regions the competition for food z 
been decidedly in favor of the exogens, the endogens have su 
into the lowly grasses, and the ferns into feeble inmates of ot 
situations. Even the more hardy conifers have been driven the 
before the march of the exogens, and have retreated eo 
marshes and the cold and partly barren mountain sides, W s 
the character of their organization seems to give them an 
