112 



THE AMERICAN BOTANIST 



that the flowers began to be used as distinguishing structures, 

 but time has confirmed the value of this method and it is not 

 likely to be abandoned. 



Flower Colors Mixing. — One of the ideas most diffi- 

 cult to eradicate from the mind of the average individual, is 

 that flowers of different colors, when planted together, will 

 mix. The whole matter of cross pollination is still a mystery 

 to him. Having heard that plants cross, or mix, in some way, 

 he assumes that it is the plants that affect one another. In 

 some cases he even goes so far as to imagine that plants of 

 widely different relationships can thus affect each other. As 

 any botanizer knows, however, plants of the same species with 

 various colored flowers may be grown intermingled for long 

 terms of years, without the least fear that the colors will mix. 

 If the plants are annuals or other short-lived plants that have 

 to be reproduced from seeds, however, this is quite another 

 matter, for in seed production, the flower has to be pollinated, 

 and if the pollen from a flower of one color falls on the stig- 

 mas of a flower of another color, a mixed progeny will of 

 course result, though this is often not manifested in the plants 

 of the first generation. Tulips, hyacinths, nasturtiums, sweet 

 peas, pansies and many other plants with multicolored flowers 

 may be planted in close juxtaposition without any change in the 

 flowers whatever. 



Growth and Reproduction. — Plants as well as animals 

 are made up of small bits of protoplasm called cells, and all 

 growth consists of the division and subsequent increase in size 

 of such cells. In the lower forms of life any cell may thus di- 

 vide, but in higher forms it commonly happens that only certain 

 cells are concerned in such activities. In the trunks of dicoty- 

 ledon trees, for instance, the chief growing tissue is the cam- 

 bium layer situated between the wood and the bark. In the 

 simplest plants, which consist of single cells, growth and re- 

 production are practically synonymous since when the cell di- 



