1 68 Mr. Thomas Hick on 



In the outer cortical zone, we again recognise the thin- 

 walled tissue at o, but its bulk is still small. In it are a few 

 lacunae, /, but whether they are natural air-canals, or due to 

 accidental rupture, there is nothing to show. The thick- 

 walled elements, on the other hand, have increased con- 

 siderably, and now form a dense thick hypodermal layer, s, 

 which appears to have been sclerenchymatous. The 

 elements of this layer are not arranged in radiating series, 

 nor are they grouped in triangular bundles, thus differing 

 from the corresponding tissues described by Williamson. 1 



On the whole then, it would seem that the structure of 

 the cortex, as seen in the primary stem of this type of Cata- 

 mites, retains its characteristic features for some time after 

 secondary thickening has set in, the chief modification, apart 

 from the doubtful lacunae, being the increase in the 

 mechanical tissue. 



Reviewing the facts as set forth in what has gone 

 before, botanists will probably be most struck with the 

 remarkable features of the tissue which makes up the inner 

 zone of the cortex. From what I have seen of it, in many 

 preparations, I am convinced that it is an important tissue 

 both in a morphological and a physiological sense, though 

 I cannot as yet specify in what its importance consists. It 

 is not confined entirely to the stem, but is found also in the 

 leaves, where it forms a conspicuous layer, which extends 

 from one edge to the other, and runs from base to apex 

 beneath the epidermis on the convex side. Finally, an 

 identical layer is present in a similar position in the sterile 

 bracts of C alamo stacliys Binneyana, as I have shown else- 

 where, 2 awakening the suspicion that in the type of 

 Calamites here considered we have the plant that bore 

 Calamostachys Binneyana as its fruit-spike. 



1 Phil. Trans., 1878, p. 324; Ibid, 1881, p. 465. 

 ^Proceedings of the Yorkshire Geological and Poly technic Society , 1893, p. 287. 



