Kctshyap. — Notes on Equisetum debile , Roxb . 445 
single cell may show radial bands on three or four of its walls or two bands 
on the same wall. 
2. The prothallium. If the spores are sown thickly the prothallia 
remain small and show one growing point only and usually bear only one 
kind of sex organ. If the spores germinate at a distance from each other, 
leaving enough space for the prothallia to develop fully, the latter become 
very large and develop a meristem all round on the circular margin. 1 It is 
possible to keep the prothallia growing for a few months longer than their 
natural period of life by removing the embryo and protecting the prothallia 
from heat, and probably possible to keep them growing for more than one 
year. 
1 These prothallia bear archegonia at first and develop antheridia later on. 
H h 2 
