242 BOTANICAL GAZETTE [march 



type. As far as the longitudinal walls are concerned, the 

 opposite view, that of the persistence of the membrane in the pits, 

 was upheld by Halft (6) for "all the vascular cryptogams." He 

 demonstrated by physical and microchemical means the presence of 

 a limiting membrane in both the side and end walls of a large 

 number of ferns. Halft's work was verified in the followii 



Miss 



Nottingham. Judging from 



my own results with members of this group, I should think that 

 Halft had shown the "real" nature of the elements in the ferns. 

 Comprehensive as is his work, however, his statement is more so, 

 for no mention is made of a study of any member of the Ophio- 

 glossaceae. Miss Bancroft, also, in corroborating his work, omits 



family 



a drawing from the rhizome of Ophioglossum vulgatum, 

 typical membrane in that form. In sections stained 

 nitrate and ammonia and counterstained with methyl- 



scalariform 



membrane 



same 



Here 



toxylin accentuates the broad primary wall within the spools, and 

 stains only faintly the membrane in the pit. The latter, indeed, 

 often appears to be somewhat lignified, taking to a certain extent 

 the red stain of the lignified pit borders. The petiole as it leaves 

 the rhizome exhibits a similar type of membrane. 



It was with the greatest difficulty that the membrane in Hel- 

 minthostachys was stained sufficiently for clear demonstration. 

 After prolonged staining with the ordinary haematoxylin and 



form 



remained so vague 



finally 



malachite green, Martius 



fuchsin, originally used by Dr. Pianeze for cancer tissue. The 



Mo 



May, 1914) as a differential stain 



Fig. 18 shows the condition in the rhizome. The lignified 



liernified 



green 



