I I 2 
L. A Boodle . 
extension of “cortical” sclerenchyma is probably a historical de¬ 
scription of this tissue 1 . 
Lastly we may combine the information derived from the two 
methods of tracing the tissues, and state that, from the node, there 
has been a downward progressive modification of a strand of stelar 
tissue into sclerotic tissue resembling the cortical sclerenchyma. 
The examples chosen in the present article are ferns, and the 
conclusions are intended to refer to ferns. In the Dicotyledons 
(leaving polyscelic forms apart) it is probable that the pith was 
originally differentiated from the stele, so that its position and the 
acropetal method in the seedling give its morphology. The effect 
of the leaf-traces on the stele has been so great, that not only has 
the vascular part of the stele come to consist of strands similar to 
the original leaf-traces, which crossed the cortex (from leaf-base to 
stele), but the differentiation in the individual strands has in many 
cases come to be basipetal, as stated by De Bary. 
L. A. BOODLE. 
1 In such a case there would be no clue to reduction, if such 
had taken place, but the description would very probably picture 
the original development of,the structure (see Boodle, Gleicheu- 
iaceae p.p. 737'73 8 ) 
MYCOLOGICAL NOTES. 
The Origin of the Ascomycetes. 
T HE question of the origin of the Ascomycetes has always been 
one of great interest, so that during the last twenty-five years, as 
our knowledge has increased step by step, the views put forward 
have been very various. There is the older view of De Bary that 
the Ascomycetes are related to the Oomycetes, especially to forms 
like the Peronosporaceae. This idea was mainly based on the 
similarity of the antheridium and oogonium of the latter group to 
the structures termed antheridium and ascogonium (oogonium) 
which are found in such forms as Spliaerotheca and Pyronema among 
the Ascomycetes. In De Bary’s time there was no direct evidence 
that any of the Ascomycetes possessed a true sexual process, but 
the form and relation of the antheridium and ascogonium seemed 
to point clearly to their sexual nature, although the evidence of 
actual transference of material from one to the other was wanting. 
