Note on the Biology of Fegatella conica. 249 
chloroplasts in the shade forms taking up this position so as to gain 
maximum intensity of light. It is quite probable, therefore, that 
decrease in light aided in the disappearance of the assimilating 
filaments, and therefore of the air chambers, just as decrease in 
light has been accompanied by decrease in assimilating tissue, whose 
function has been taken over by the enlarged epidermal cells. 
As regards the variation in form of the thallus found in the 
decreasing light intensities, it is interesting to compare Miss 
Greenwood’s results with Pellia epipliylla .’ She found that those 
thalli growing in shaded places take on a narrow slender shape, and 
those having a greater exposed surface fork and fork again and 
broaden out horizontally. 
Further, Cavers 2 mentions that thalli of Fegatella are elongated 
and narrowed in darkness. Bolleter 3 however correlates elongation 
and narrowing of thalli of Fegatella with conditions of moisture. It 
is quite probable that both darkness and moisture have been instru¬ 
mental in producing this variation of form. 
Summary. 
Thalli of Fegatella conica without air chambers were found in a 
hole in a bank. The absence of air chambers is concluded to be due 
to the combined effect of darkness and moisture. For in thalli 
growing in increased intensities of light there is a gradual decrease 
in the number of air chambers per unit of surface area, and in the 
size of those air chambers. The final disappearance, however, 
seems to be dependent on the factor of moisture, for only in those 
forms shewing marked adaptations to a moist habitat were the air 
chambers totally lacking. This case adds to the number of 
Marchantiales already known as occurring without air chambers. 
The above piece of work was carried out in the Botanical 
Laboratory of Westfield College, under the supervision of Dr. E. M. 
Delf, to whom I wish to express my thanks. 
Westfield College, 
Hampstead, London. 
T Helen H. Greenwood. “Some stages in the development of Pellia 
epipliylla." The Bryologist, Vol. 14, 1911. 
2 F. Cavers. Ann. Bot., Vol. 18, 1904, p. 97 
3 F. Bolleter. Loc. cit, 
