XIV.] THE RESULT OF THE STRUGGLE. 261 



marked unlikeuesses ; and I shall allow the plat to 

 remain without defilement, that I may observe the 

 conflict in the years to come, and I shall also sow 

 seeds from some of the unlike plants.* From all 

 these facts, I am bound to think that physical en- 

 vironment and struggle for life are both powerful 

 causes of variation in plants which are born equal. 



Still, the reader may say, like Weismann, that 

 these differences were potentially present in the 

 germ, that there was an inherited tendency for the 

 given red -root to grow three feet tall when eighty - 

 five other plants were grown alongside of it in 



*Prom two of the red-root (Amarantus retrofiexus) plants of different stature, 

 seeds were sown in pans in the greenhouse. One of the plants was twelve inches 

 high and had a spread of branches of nine inches. The other was twenty-four 

 inches high and thirty inches broad. The seeds from each were thoroughly ripe 

 and the plants were matured ; yet of the seeds from the smaller plant only a few 

 had sufficient vitality to germinate, and all the plants which did appear were vei-y 

 much smaller in stature at maturity than the seedlings of the larger plant. The 

 difference in vigor between the two lots was most remarkable, showing — what 

 every gardener knows to be true — that the acquired habit of a plant generally has 

 a powerful effect upon its offspring. 



As this Essay goes to press, June 23, 1896, this little plot presents a most inter- 

 esting aspect. It is tangled full of luxurious herbage, but the passer-by would see 

 little else than a clump of red clover, and here and there, about the edges, a rag- 

 weed. My gardener remarked that the plat contains less plants than last year. 

 Yet here is the census : 



Black Medick 3 plants. 



White Clover f> 



Red Clover 11 



Red-root . • ' • . . 78 



Ragweed 135 



Pigweed 1 



Shepherd's Purse 2 



Mallow (Malva rotundi folia) 6 



Sow-thistle {Sonchus oleracens) 1 



Alsike Clover 7 



Spears of grass, about 50 



299 

 Notwithstanding all this marvelous population, the greater part of the space 



