36 
(3iii() Ijiologjcal Survey 
lichens (6). Stahl chose members of the same family for the first im¬ 
portant work on sexual reproduction in lichens (7). Sturgis (8) and 
Baur (4) have since confirmed Stahl's results. Miss Bachman (1 and 2) 
has found in a member of the Collcinaccac an interesting condition with 
respect to the morphology and the behavior of the sexual reproductive 
tracts and has obtained in the same plant the only important cytological 
results thus far secured in the study of the sexual organs of lichens. The 
results obtained by these workers are known to many botanists, have been 
considered in part in the first paper of this series, and need no further 
discussion here. 
In working out a new taxonomic method, there is a distinct ad¬ 
vantage in considering a group of plants in which many botanists are 
interested. However, our prime motive in selecting the Collemaccac was, 
as explained above, to attack first a family of lichens, the treatment of 
which as fungi probably presents as many difficulties as any that could 
be selected. The species of this family grow mainly within the algal 
hosts instead of containing these hosts in a limited area within somatic 
tracts of the parasites as do the great majority of lichens; and the de¬ 
scriptions of gross characters hitherto given as morphological features 
of members of the Collemaccac belong largely to the algal hosts rather 
than to the lichens themselves. Finding a satisfactory way to obviate 
this difficulty and devising a new method for the study of the minute 
morphology of these lichens have required spending much time and energy 
on details, some of which have proved to be of little if any taxonomic 
.value and have not been included in the results presented in this paper. 
One year was given to working out a method, which, in the last two years, 
has been further elal)orated in the studies of the Collemaccac of Ohio 
presented herein. 
In connection with many difficulties encountered, it is fortunate that 
the tissues of members of the Collemaccac appear more distinctly in 
sections than do those of the majority of lichens. This condition has 
made it comparatively easy to study most of the details with respect to 
structure of cortices, medullse, sexual reproductive tracts, and apothecia. 
In a few instances, we have resorted to imbedding and serial sectioning; 
but most of our results have l^een obtained by free-hand sectioning with 
the razor. Flemming’s triple stain, Delafield’s haematoxylin, and safranin 
..were used with good results; but we depended mainly on the solution 
of iodine which is used commonly in the study of lichens. Other 
reagents used were water, potassium hydrate, Schulze's macerating fluid, 
and alcohol. For macerating, potassium hydrate was found more satis- 
