2i6 NATURAL SCIENCE. V^; 



other liand, consists of the secondary or exogenous xylem, and it is 

 from this structure that the monarch bundles of the rootlets are 

 derived. Two such absolutely different zones of the wood could not 

 supply homologous organs. 



I repeat, therefore, my conviction that our true British examples 

 of Stigmaria are, and can be none other than, true roots ; and, so far 

 as my limited acquaintance with the German specimens enables me 

 to form an opinion, they appear to belong to our British type. That 

 some different objects may be discovered in the French collieries, I am 

 alike unable to affirm or to deny ; but I am compelled to entertain 

 doubts on the subject from more reasons than one. I am unable to 

 reconcile the descriptions of M. Renault with those of Grand' Eury. 

 I cannot obtain any clear and definite account of the nature of the 

 bulbs supposed to be developed at the under surface of the so-called 

 rhizomes. In my Monograph (Joe. cit., fig. i8) I have described roots 

 of our Stigmaricr from a specimen which cannot have been much more 

 than one-fifth of an inch in diameter, to the large Clayton example 

 in the Owens College Museum, which extends nearly thirty feet from 

 side to side ; yet in none of these do we discover the faintest trace of 

 any bud or bulb, nor yet of any indication of a point to which such a 

 growth could have been attached. The idea of the possibility of 

 some gigantic protonemal condition having been the first product of 

 the germinating Lepidodendroid spore has for some time past 

 suggested itself to my mind, such a protonemal state being repre- 

 sented somehow by the "Rhizomes" and "Bulbs" of which the 

 French authors speak ; but, until we obtain more exact details and 

 figures of these French structures than we at present possess, I must 

 confess to a large measure of doubt being left on my mind in 

 reference to the entire subject of these supposed discoveries and 

 the conclusions based upon them. 



Further, when Grand' Eury is describing what appear to me to 

 be the French representatives of our British Stigmaria', he defines 

 their roots as " court." One of these roots, which I measured at 

 Clayton, was 37 ft. 4 ins. long, and while at its thick base the root 

 was more than 8 ft. in circumference, it tapered away at its apex to a 

 mere point. 



My valued friend tells me that there is really less difference 

 between his views and mine than I believe to exist, and the 

 acquisition of more exact details and clear definitions than we have 

 yet got may prove that this is the case. He is too indefatigable and 

 distinguished a geologist, as well as too conscientious a man, to make 

 it possible to doubt that he is in the possession of some facts which have 

 no parallels in Great Britain. How far what at present appears to be 

 his interpretation of those facts will prove correct, yet remains to be 

 ascertained. Personally, I am yet as incapable of understanding 

 them as of rating them at their true value. 



W. C. Williamson. 



