40 REPRODUCTION 



group of hydroids, some of whose members illustrate 

 budding, also contains forms which send out from the 

 parent special tissues that grow over and attach to the 

 solid support, often very tightl3^ This serves to hold the 

 animal fast, but this is not all. From this tissue may 

 grow up at various distances, depending on the species, 

 and probably on the nutrition and other conditions of life, 

 new hydroids like the parent. Several other groups of 

 animals somewhat less known have very similar habits. 

 In buds proper there is an actual outgrowing of the body 

 tissues into the bud; in this case the bud, if it is to be 

 called so, arises from the attaching tissue rather than from 

 the body itself. 



4. The Value of Stolons. There is more meaning in 

 this stolon-forming habit than mere multiplication. It is 

 a special method whereby a plant or an animal that has 

 once got hold in a locality that furnishes abundant food 

 for its rapid growth can rapidly take possession of nearby 

 territory, and can spread out more rapidly than if it 

 depended on seeds and spores. This method acts 

 somewhat automatically to adjust the organism to 

 favorable conditions. If the place is not favorable, the 

 parent plant will not have energy to form runners, but will 

 at once produce spores or seeds which may be carried from 

 the spot to a more favorable one. If it is favorable, there 

 will be energy enough for both methods of reproduction, 

 and the organism will take intense possession of the 

 nearby territory as well as scatter spores. Spores lead to 

 wide spreading; runners lead to full possession of a 

 locality. 



5. Tubers. Tubers such as we find in Irish potatoes 

 present a very interesting phase of reproduction. Irish 

 potatoes have seeds and may be propagated by these; 

 but in our cultivation of the potato we do not use this 

 method. From the old plant some stems, not roots, arise 

 and grow under ground instead of coming out as others 



