- 25 - 



At the end of about eleven weeks the protonema had 

 given rise to distinct rhizoid branches, and an abundance of 

 bnds had been formed. Soon after this the old protonema 

 began to turn brown and die. During this period of growth, 

 the extensive network of protonema filaments had not been 

 entirely produced by the direct growth of the originally 

 formed main axes, but a multiplication of the protonema had 

 occurred. Certain side branches seemed to be specialized 

 for this purpose, since the cells increased in size, developed 

 a very abundant Chlorophyll content, rounded themselves 

 somewhat until they were about barrel-shaped, and then sepa- 

 rat ed from the branches either singaly or several together. 

 These separated cells then gave rise to new protonema. 

 Goebel ! mentions the pover of a protonema , species not 

 known, to separate in this way when the culture was allowed 

 to dry. In the case of Barbula however, the Splitting away 

 of the cells was not due to drying out, since the culture 

 was supplied with nutritive Solution for the entire period 

 of growth. 



The protonema originated oulj from the basal cells of 

 the leaf, generally either from the very end cells or from 

 those next the margiu. The cells of the basal portion are 

 much longer than those occupying the apical portion, and 

 the question now presented itself as to whether the small 

 cells of the apical half of the leaf were capable of growing 

 out into protonema. In order to determine this the basal 

 portions were cut away from a series of leaves , and both 

 apical and basal portions retained in culture. The result 

 was that no protonema were produced from the apical portions 

 of the leaves, while the basal portions only produced proto- 

 nema from the cells of the proximal end. The protonema 

 growth was generally from cells occupying the periphery, 

 but occasionally one originated from a cell a little removed 

 from the margin. These experiments then show the power 

 of regeneration to be confined to the larger cells of the 

 leaf base. 



1 Sitz.-Ber. d. mat.-phys. Classe d. k. Bayer. Akad. d. Wiss.36: 641. 1896. 



