Evans .— Vegetative Reproduction in Metzgeria. 293 
The germination has been observed only in the early stages, and agrees 
essentially with what has been described for most of the preceding species. 
The young thallus, which results from the activity of the apical cell, is 
usually narrower than the gemma (Fig. 15, d), although the change from 
one to the other is often gradual. The narrow condition persists for a 
variable distance, and then the young thallus becomes broader again. 
Scattered hairs, like those on the gemma, continue to be produced, and 
a forking of the thallus is sometimes to be observed. Although in some 
cases the young thalli had attained a length of a millimetre or more, 
no further differentiation and no evidences whatever of dorsiventrality had 
become apparent. In all probability the peculiar marginal cells and hairs 
of the mature thallus mark a very late stage of development. 
Metzgeria fruticidosa , (Dicks.) comb. nov. 
Since most recent writers have considered M. fruticidosa to be nothing 
more than a form or variety of M. furcata its geographical distribution is 
very incompletely known. It has been recorded in Europe from a number 
of scattered localities, but the only American station which the writer can 
quote at the present time is near Aberdeen, Washington, where the plant 
was collected on February 18, 1909, by Foster (No. 944). The description 
of the gemmiparous branches (with the accompanying figures) is drawn 
largely from these specimens, which were kindly supplied by Miss Haynes. 
Material from Salem in Baden, Germany, collected by Jack (Hep. Europ. 
No. 357), and from Cherbourg, France, collected by Corbiere, has been used 
for comparison. In contrast to the species already described M. fruticidosa 
has strongly specialized gemmiparous branches. Other species with similar 
branches have already been alluded to in the introduction, but unfor¬ 
tunately none of these have been available in sufficient quantity for detailed 
study. 
The normal branches in M. fruticidosa are prostrate and divide by 
forking. The costa is usually bounded both antically and postically by 
two rows of cells (Fig. 16, a), although the number of postical rows is 
sometimes three or even four. The number of internal costal cells averages 
about ten in cross section. The wings are plane or slightly convex and 
attain a width of perhaps ten cells. On the postical surface of the costa 
and along the margin are numerous straight hairs which often act as 
rhizoids. Scattered hairs on the postical surface of the wings are some¬ 
times present as well. Most of the marginal hairs occur singly, but they 
are sometimes geminate. They are apparently never displaced to the 
postical surface. In the vicinity of the apex slime papillae of the usual 
type may be demonstrated. According to most writers the fresh plants 
are green, but they often become tinged with blue after being dried. 
When a branch becomes gemmiparous, it gradually curves away from 
