MancJiestcr Memoirs, Vol. liv. (1910), No. 11, 3 



phragms we have a marked " shortening-up " of the other- 

 wise elongated medullary cells (see Photo. 2 of Plate). 

 On the contrary, none of these features are found at the 

 level of the sporangiophores, where, as Dr. Scott (William- 

 son and Scott '94, p. 906) long ago pointed out, there is 

 " scarcely any modification of structure as compared with 

 the internodes " — we may say none which is not absolutely 

 inevitable. There is no trace of " nodal wood," no 

 obliteration of the carinal canals, and no modification of 

 the medulla. In impressions of the closely-allied Calaino- 

 stachys Liidwigii, Weiss (Weiss '76, p. 41) states that 

 there '*'? no trace of jointing at that level (" von querg- 

 liederung an dieser stelle keine Spur"). These facts 

 appear to me to offer the gravest difficulty to the inter- 

 pretation of the sporangiophores as modified leaves. 



In confirmation of the above, and passing to the next 

 point, it must be remarked that in the rare event of the 

 sporangiophore-trace being seen to part company with 

 the main vascular bundle, it merely separates from the 

 outside of the latter and causes no gap, whereas the bract- 

 trace clearly originates from the main protoxylem-mass at 

 the node and passes through the main bundle. 



The true relations of the sporangiophore-trace are 

 extremely difficult to determine. This is largely due to 

 the great delicacy of the vascular tissues in the neigh- 

 bourhood of the insertions of the sporangiophores and 

 their consequent very imperfect preservation in nearly all 

 cases. The best example I have seen is a transverse 

 section (O. 291, Manchester Museum Coll.) in which 

 portions of four traces are seen just separated from the 

 stele, the remaining pair appearing as projections from 

 the other stelar bundle. By careful focussing, each of the 

 free traces can be made out to be slightly arched, ascend- 

 ing slightly from the stele and descending again towards 



