262 PLANT PHYSIOLOGY 



many cells, are never formed by the fusion of cells. Each 

 of the cells cut off is able, by successive divisions, to form 

 a new plant like its parent. The one parent or parent-cell 

 or mass of cells gives its own matter and energy, its own 

 protoplasm, to the new individual. Because the substance 

 of only one parent goes iuto the offspring there is a radical 

 difference between this non-sexual mode of reproduction and 

 the sexual mode. With the transfer from parent to off- 

 spring of its own substance and means of obtaining energy 

 there are transferred also the same degree of sensitiveness, 

 the same powers of reaction to stimuli, and the results of 

 the reaction to stimuli already accomplished by the living 

 protoplasm of the parent. The offspring are not only like 

 the parent, they are really branches or continuations of 

 the parent. There is introduced into the new individual 

 nothing new, but as soon as it is cut oft from the parent, 

 it is subjected to influences some of which may be new 

 and different and which will stimulate the individual to 

 corresponding reactions. The gemmules of certaiu Mar- 

 chantiacese, the lateral branches which gradually become 

 the separate plants of AzoUa, the runners of the straw- 

 berry, etc., are means of non-sexual (and vegetative) repro- 

 duction. The matter and energy, the substance and struc- 

 ture, of the one parent are carried directly over into these 

 offspring. The condition of the parent at the time of re- 

 production, representing the resultant of all its reactions 

 to all the stimuli to which it has been subjected, is also 

 the condition of offspring made in this way. This fact is 

 still clearer in such a plant as Spirogyra, which, breaking 

 up into the cells of which the filament is composed, * forms 

 new individuals which share its qualities by sharing its sub- 

 stance and structure. In many other low plants the proc- 

 ess of vegetative reproduction is as simple and clear as 

 possible. Similar but multicellular bodies vegetatively re- 

 produce higher plants, continuing and at times multiply- 

 ing the species with nearly or quite the same characters 

 in the new as in the old individuals. The runners of straw- 



* Benecke, W. Mechanismus und Biologie des Zerfalles der Conjugaten- 

 faden in die einzelnen Zellen. Jahrb. t. w. Bot., 32, 1898. 



