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DR JOHN M'LEAN THOMPSON : A FURTHER CONTRIBUTION 
Text-fig. 9 . Text-fig. 10 . Text-fig. 11 . 
are particularly thickened. The mesophyll is well supplied with intercellular spaces, 
and the bundle-sheaths have mucilaginous contents. The stomata are numerous, 
and are restricted to the lower surface of the pinna. A curious feature is shown in 
some cases by the epidermal cells surrounding the stomata. They include starch 
grains similar to those present in the mesophyll (text-fig. 3). The disposition of 
the sporangia upon the sympodial vein-system has already been described, and 
the careful protection of the sporangia against xerophytic conditions is manifest. 
As in the first materials examined, so also in the second, the margins of the fertile 
pinnae are so revolute that the sporangia are in an almost closed chamber (text-fig. l). 
The entrance to this chamber is much reduced by short thick-walled hairs borne on 
the margins of the pinna (text-fig. 2). The outer walls of the upper epidermal cells 
Text-fig. (i. 
