24S 
Annie C. May brook. 
are much reduced, and the pores fewer. Cavers 1 noted that in 
submerged plants of Mavchantia the air chambers shew great 
reduction. Reduction in number and size of the air chambers of 
Fegatella conica has been correlated with both factors of light and 
moisture. Cavers 4 says, in connexion with the asexual reproduction 
of this genus, “ when cultures were made in darkness ” ( i.e ., cultures 
of cut pieces of thalli on damp soil) “ new shoots were formed quite 
as freely as in the light, but they were long and narrow, and did not 
grow into normal plants with typical air chambers and scales. On 
being brought to light they gave rise to normal plants, otherwise 
they remained abortive after attaining a length of 2 to 3 cm.” 
Bolleter 3 noticed that when thalli of Fegatella conica were found 
growing on very damp soil, the air chambers were reduced in 
number and size. He does not mention total disappearance, 
however. 
In the Fegatella found in the cavity already referred to in this 
paper it is obvious that a decrease in light has been an important 
factor in causing the reduction in number and size of the air 
chamber (see Table). The factor of moisture, however, has 
probably played an important part in the final disappearance of the 
air chambers. The similarity in structure of Forms IV and V and 
the possession by the former of distinctly aquatic modifications, 
namely, the absence of ventral scales, tuberculated rhizoids, and 
mucilage sacs and canals, lead one to suspect that the simplicity 
of structure was brought about in the first place by conditions of 
moisture. Cavers 4 and later Bolleter 5 concluded that the function 
of the filaments of the air chambers is that of transpiration, the 
former having proved experimentally that evaporation of water is 
localised in these pointed cells. It is quite conceivable, therefore, 
that an increased water supply would be an important factor in the 
elimination of the air chambers. These authors agree in stating 
that the chloroplasts are confined to the basal portions of the 
filaments. In Form III and in the transitional form here described, 
however, chloroplasts were distinctly present in the neck. In the 
transitional form they were even limited to the neck. This appears 
to point to an assimilatory as well as a transpiratory function, the 
r F. Cavers. New Phytologist, Vol. 9, 1910, p. 108; Ann. Bot., Vol. 18, 
1904, p. 87. 
2 F. Cavers. Ann. Bot., Vol. 18, 1904, p. 97. (The italics are mine). 
3 E. Bolleter. “ Fegatella conica." Beihefte zum Bot. Centralbl., Band 
18, 1905. 
4 F. Cavers. Ann. Bot., Vol. 18, 1904, p. 91. 
* E. Bolleter. Loc. cit. 
