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whether it was possible for the cells from the costal region 

 to give rise to buds, the lateral halves were split away from 

 the costa, and both portions cultivated. The result was that 

 buds appeared from the costal region as from the lateral 

 halves, showing that in the whole leaf the power to produce 

 buds was only suppressed. Again with reference to the 

 power of young and old or fully mature leaves to regenerate. 

 Series of leaves from the mature to the very smallest that 

 could be dissected from the end bud were subjected to 

 culture, with the result that the leaves from ordinary size 

 to about half way through the series produced buds and 

 rhizoids in abundance. Those from this point on to the very 

 minute leaves produced only rhizoids, and these mostly from 

 the region of the costa. It was evident that the plastic 

 material was not present in sufficient abundance to produce 

 a further development, or that being an embryonie organ, 

 the young leaf used its available supply of food material 

 towards the growth of its own cells. 



So far as I have observed, the leaves of Mnium in nature 

 never give rise to rhizoids when still in connection with 

 the stem. In order to aiford experimental proof of this, 

 whole plants were subjected to exactly the same conditions 

 as the detached leaves, but no rhizoid production resulted. 

 Again, it might be thought that the formation of rhizoids 

 and buds was called forth by the injury to the leaf. That 

 the cutting of the leaf is not effective in the production 

 was shown by those experiments in which the leaves were 

 cut and still left in connection with the stem, even in these 

 leaves no new growth resulting. Another series of experi- 

 ments was made in which the costa was cut near the base 

 of the leaf while the lateral halves were still left in 

 connection with the stem, with the idea that the severing 

 of the costa might cut off the path for the transport of 

 food material. No rhizoid growth was called forth, and 

 hence the previous experiments show that nothing but the 

 complete Separation of the leaves from the the stem is able 

 to call forth the power of the leaf to regenerate. When 



