82 Appendix. 



sition contrary to reason as well as to all human experience and 

 observation. 



Seeds in or on the ground either grow or rot, very soon after 

 the earth becomes sufficiently warm and moist to promote vege- 

 tation. Seeds, planted in the fall or early in the spring, do not 

 lie dormant until July or August, and then germinate and grow. 

 Gardens in cities are generally kept so free from weeds that none 

 are allowed to go to seed ; and yet the following year, if the 

 ground be rich and the season be wet and warm, thousands of 

 weeds spring up more in the latter part than in the fore part 

 of the season ; and it is impossible to account for them, unless 

 they originate and grow spontaneously, and without seed. How 

 quickly fire- weeds spring up in the woods where a log- heap or a 

 pile of brush has been recently burned, and all seeds killed by 

 the fire. Weeds which grow from seeds produced the previous 

 year, usually spring up in May or early in June ; but we know 

 that in a warm and wet season, there are from five to ten times 

 as many weeds springing up in g .rdens and in corn and grain 

 fields and pastures, in the months of July, August and September, 

 as during the months of May and June. Large quantities of 

 summer grass and weeds grow in corn fields after the last cultiva- 

 tion of the corn in July. The fact that the most of the weeds 

 that grow each year in cold and temperate climates, spring up 

 after the first of July, constitutes unanswerable evidence that 

 those coming up late in the season do not come from seeds of 

 parent plants, but are spontaneous productions of the earth. 



Mushrooms usually spring up in the latter part of the sum- 

 mer, upon heaps of manure which have been fermenting for 

 weeks in succession ; and upon droppings of manure upon old 

 pastures. It is very evident, that the most of them do not come 

 from seed of parent plants grown the previous year ; for, if such 

 were the case, they would come earlier in the season. I can see 

 no reason to doubt, that they are the spontaneous productions of a 

 living principle, acting upon the manure out of which they grow. 

 And so it is, with the natural grasses and herbs, shrubs and trees 

 of every country with the mosses which grow upon trees, bar- 



