CHILEAN SPECIES OF METZGERIA. 



305 



of gemmae will at once serve to distinguish M. epiphylla from M. dc- 

 cipiens. The gemmiparous branches seem to be always narrower than 

 the normal vegetative thalli, the reduction in width being confined to 

 the wings, but at first no other signs of differentiation are evident. 

 With the appearance of the gemmae (Fig. 8, D) the wings become still 

 narrower and the branches curve away from the substratum, their 

 growth in length being sooner or later brought to an end. In extreme 



Fig. 8. Metzgeria epiphylla Evans. 



A. Portion of a thallus, dorsal view, X 50. B. Cells from outer layer 

 of a capsule- valve, X 300; m, median wall of valve. C. Cells from inner 

 layer of a capsule-valve, X 300; m, median wall of valve. D. Gemmiparous 

 branch, dorsal view, X 50. E, F. Gemmae about ready to separate, X 100. 

 G. Germinating gemma, X 100. The figures were all drawn from the type 

 material. 



cases the wings become reduced to a width of only two or three cells, 

 but the growth may cease while the wings are considerably broader. 

 No cases have been observed where a gemmiparous branch had 

 reverted to a vegetative condition, and yet it would not be surprising 

 if such a change occasionally took place. The gemmiparous branches 

 are flat or slightly convex when seen from the dorsal surface and some- 

 times branch after the production of gemmae has begun. 



