Manchester Memoirs, Vol. Ivii. (191 3), No. 16. 3 



From the earlier specimens of young Lvginodendron 

 roots which I examined, I conchided that it was probable 

 that they agreed with the Marattiaceous type, but the 

 further specimens I have now had an opportunity of 

 examining, have led me to somewhat modify my view. 

 Even in the case of existing plants, it is not always easy 

 to be certain whether a growing point possesses a single 

 apical cell, and, in the case of fossil root tips, of which only 

 one longitudinal section is usually available, it is still more 

 difficult, because it is often impossible to tell whether the 

 section under examination is strictly median or not. In 

 the case of a transverse section, too, if a group of initials 

 appear, it is quite possible that the section has been taken 

 below the actual apical cell. 



Fig. I is an accurate camera lucida drawing of one 

 of the best longitudinal section through the root-apex of 

 Lyginodendron, and is the same as the one referred to 

 above as figured by Stopes and Watson. {Phil. Trans., vol. 

 200.) It is on slide R. 646 in the collection of the Man- 

 chester Museum, formerly in the possession of the late 

 Mr. Thomas Hick. The slide is prepared from the 

 well-known Dulesgate material, and contains numerous 

 fragments of stem, roots, and petioles of Lyginodendron. 

 The total length of the portion of the root-tip, including 

 the various layers of the root cap is only -65 mm., the 

 widest portion of the root being •21 mm., while near the 

 apex the root narrows down to '07 m.m. 



To enable an estimate to be made of the extreme 

 delicacy of these lateral roots, it may be stated that an 

 average-sized root-tip of Aspidiiini is from two to three 

 times the width of this particular root of Lygi^iodendron. 

 Nor is this one the most delicate, for other longitudinal 

 sections measured about the same distance behind the 

 apex varied from -16 to ■24 mm. in diameter. 



