512 MANUAL OF BOTANY 



were intact, but its manifestation in the form of curvature took 

 place as an after effect, even after the stimulus had altogether 

 ceased to act. 



CHAPTEK XVIII. 



REPRODUCTION. 



The phenomena we have hitherto been considering all concern 

 the life of the individual plant. As this, however, at the best 

 is comparatively limited, we find plants endued with the 

 power of giving rise to new individuals. The process of ori- 

 ginating each new individual from its parent or parents is 

 known as reproduction. 



We have alreadj- seen that this process may be brought 

 about in one of three ways. In the simplest cases, in what is 

 known as vegetative reproduction, no special cell is produced 

 for the purpose, but some part of the parent becomes detached 

 and grows into the new individual at once. ^Ye see this easily 

 in the reproduction of the lower Fungi, such as yeast, where the 

 cell divides into two, which almost or quite immediately 

 become free from each other, each being a yeast plant. It can 

 be noticed througli all the families of the vegetable kingdom, 

 though as we advance upwards in the scale the new body 

 becomes more and more complex. We have the gemmae of 

 certain Algte and Bryophytes, which are multicellular ; we have 

 in many Mosses branches which become detached by the dying 

 off of the shoot behind them ; in many Ferns buds are de- 

 veloped upon the pinnae of some of their leaves, which when 

 separated from the latter grow into complete ferns. In the 

 Phanerogams we find this method illustrated by cuttings, which 

 are pieces of the stem bearing buds ; these, when detached and 

 planted in suitable soil, put out adventitious roots from the 

 base of the cutting, and develop into plants like the original one. 

 Another instance is afforded by the buds which many leaves, 

 notably those of Brijophyllum, put out when wounded. These 

 also develop adventitious roots, and 3"0ung plants arise which 

 become independent. Other plants produce underground buds, 

 tubers, &c., as already noticed. One of the chief features of 

 vegetative reproduction is that the new plant represents the 

 same phase of the life cv'cle as its parent did. Thus the 

 gemmae of Mosses, which arise on the gainetophyte, give rise to 



