278 PLANT PHYSIOLOGY 



in, but unless these give rise to spore or other resting 

 stages all the species will be locally destroyed when the 

 puddle dries. Vegetative reproduction is in many cases 

 the most effective means of multiplying the number of in- 

 dividuals, but it is seldom effective in securing wide dis- 

 persal or in insuring the permanence of the species. These 

 two needs are generally met by the formation of non- 

 sexual or sexual spores and their products (seeds, fruits). 

 The non-sexually formed spores of the ferns, and arche- 

 goniates generally, and of the lower plants, fungi and algae, 

 are especially adapted by their small size and in various 

 special ways to secure wide dispersal. They may or may 

 not be very resistant. According to the plant which forms 

 them, and according to the season at which they are formed, 

 they will be resting-spores or such as must germinate at 

 once if at all. 



New individuals vegetatively produced, and those from 

 germinating non-sexual spores, wiU contain material from 

 their single parent only. By sexual means, there are united 

 in the offspring substances from both parents. Among the 

 lowest plants ( and animals ) the visible differences between 

 the two parents are only slight. In higher plants, however, 

 where the new individuals are formed by the fusion of 

 sexual elements themselves obviously unlike, formed in 

 organs and by parents also obviously unlike, it is evident 

 that a new balance of forces and matters may be, but not 

 necessarily will be, possessed by the offspring. Maternal 

 and paternal characters may offset or intensify one another ; 

 maternal influences during the development of the spore or 

 embryo may or may not neutralize the paternal influence 

 carried into the germ-cell by the sperm. The offspring 

 sexually produced, representing a new adjustment, may be 

 better adapted to prevailing conditions than was either 

 parent. These are all possibilities, seldom probabilities, 

 almost never certainties. The chances are even that the 

 offspring will be like the average of the species. Some may 

 be worse, a few may be better, but unless the better, when 

 it comes their turn to reproduce sexually, mate with others 

 equally good, their offspring will almost certainly be like the 



