6 Hick, on Rachiopteris cylindrica, Will. 



to warrant the provisional conclusion that the bodies in 

 question are really constituents, or derivatives, of the 

 normal cell contents and not alien immigrants from 

 without. On this view their mode of origin will have 

 to be sought in the changes brought about in the 

 process of fossilisation, but with regard to this I am not 

 in a position to say anything. 



Finally, before leaving the subject, it may be worthy 

 of notice that the general occurrence and peculiarities 

 of these bodies have made it possible to use them to 

 some extent as a diagnostic character of Rachiopteris 

 cylindrica, and with such good results that determina- 

 tions first made by their aid have been subsequently 

 confirmed by more rigorous methods. 



Endodermis. 



At the innermost part of the cortex, where it abuts 

 on the central cylinder, one naturally expects to find 

 an endodermis, and the sections have been carefully 

 scrutinised for indications of its presence. The result is 

 not so completely successful as could have been wished, 

 since it still leaves some doubt whether a specially 

 differentiated endodermis is or is not always present. 

 The case appears to be somewhat similar to that of 

 Lycopodium clavatum, for we find here also thick-walled 

 elements abutting on the stele, and here a well-marked 

 endodermis cannot always be clearly recognised. But 

 in favourable sections, e.g., Nos. 104, 105 and 107, a 

 layer of thin-walled elements is found on the inside of 

 the thick-walled inner parenchyma, which, in the shape 

 of its cells, their mode of union, and the appearance of 

 the radial walls, bears some resemblance to an endo- 

 dermis (Fig. 1). Its cells are larger than, and alternate 

 with, those of the next layer on the cortical side ; and 

 they also alternate with those of the next layer within. 



