472 FACTORS OF ORGANIC EVOLUTION. 



that all living things must utterly perish. Consider the effects of a 

 frost in May. See its widespread devastation. Yet, six months hence 

 the very same trees, which are now so blackened, will defy any degree 

 of cold. And then, to make good the loss of time, these plants start 

 into activity relatively much earlier in spring than the same S])ecies do 

 in frostless climates. This very day, when frosts are not yet passed, 

 our own New York hillsides are greener with surface vegetation than 

 the lands of the Gulf States are, which have been frostless for two 

 months and more. The frogs and turtles, the insects, the bears and 

 foxes, all adjust themselves to a climate which seems to be absolutely 

 prohibitive of life, and some animals may actually freeze during their 

 hibernation, and yet these April days see them again in lieyday of life 

 and spirits! What a wonderful transformation is all this! Th'is 

 enforced period of quiesence is so impressed upon the organization 

 that the habit becomes hereditary in plants, and the gardener says 

 that his begonias and geraniums and callas must have a "rest," or they 

 will not thrive. But in time he can so far break this habit in most 

 plants as to force them into activity for the entire year. These budding 

 days of April, therefore, are the songs of release from the bondage of 

 winter which has come on as the earth has grown aged and cold. 



I must bring still one more illustration of the survival of the unlike, 

 out of the abundance of examples which might be cited. It is the fact 

 that, as a rule, new types are variable and old types are inflexible. 

 The student of fossil plants will recall the fact that the liriodendrons, 

 ginkgos, sequoias, sassafrasses, and other types came into existence 

 with many si^ecies and are now going out of existence with one or two 

 species. Williams has considered this feature, for extinct animal forms, 

 at some length in his new Geological Biology. "Many species," he 

 writes, "which by their abundance and good preservation in fossil 

 state give us sufficient evidence in the case, exhibit greater plasticity 

 in their characters at the early stage than in later stages of their his- 

 tory. A minute tracing of lines of succession of species shows greater 

 plasticity at the beginning of the series than later, and this is expressed, 

 in the systematic description and tabulation of the facts, by an increase 

 in the number of the species." " When species are studied historically, 

 the law appears evident that the characters of specific value * * * 

 present a greater degree of range of variability at an early stage in the 

 life period of the genus than in the later stages of that period." So 

 marked is this incoming of new types in many cases that some students 

 have supposed that actual special creation of species has occurred at 

 these epochs. It should be said that there is apt to be a fallacy in 

 observation in these instances, because the records which are, to our 

 vision, simultaneous in the rocks may have extended over ages of 

 time 5 but it is nevertheless true that some important groups seem to 

 have come in somewhat quickly with many or several species and 

 to have passed out with exceeding slowness. 



