1897] A NEW QUILLWORT 37 
accessible authorities has led to the unexpected result that 
apparently no investigation of this subject has been made. Dr. 
Engelmann speaks of this integument as ‘‘a crust, chalky white ;” 
Sachs is silent, as is the Micrographical Dictionary; Hof- 
meister says “the matter composing the exosporium behaves 
towards reagents like the exine of pollen grains. Sulfuric acid 
imparts a reddish color to the inner layers which are softened by 
boiling in alkaline lyes. The gelatinous layer is rapidly destroyed 
by mineral acids and caustic alkalies. Roper has observed that 
the exosporium does not contain calcium carbonate, although 
Schleiden suspected its presence from the appearance of the dry 
spores.” 
Experiments conducted with a view of becoming better 
acquainted with the chemical nature of the exosporium have led 
to the following results. The macrospores when strongly heated 
become brown and then black, and if the heat be increased to 
bright red, they still retain their form and sculpture and are 
white when cool. The exosporium is easily soluble in a solution | 
of sodium hydroxide; it gelatinizes somewhat in boiling sulfuric” 
acid, but after washing and cooling the macrospores have the 
same outward appearance as before treatment. By the action of 
destroyed, and the exosporium of many of the macrospores is 
‘able change. The 
exosporium dissolves rapidly in lego Lore and it - this oe a 
solution sodium chloride be a added, we obta 
