370 NATURAL SCIENCE. J,"^^- 



III. 

 A REJOINDER. 



There are only two or three points in Professor Williamson's 

 reply which seem to call for immediate comment, and this, of 

 necessity, must be extremely limited. 



(i.) The specimen in the Manchester Museum at Owens College 

 does not seem to me inconsistent with the statement that " the 

 external characters of Stigmaria are all in harmony with the 

 hypothesis that it is a rhizome." Much depends upon the interpre- 

 tation put upon its various features, and it is here that the divergence 

 of opinion really begins. To show, however, that I am not alone 

 in my estimate of the significance of these characters, a further 

 reference may be made to Count Solms' " Fossil Botany " (p. 288), 

 where substantially the same view is put forward. 



(2.) My references to Van Tieghem are to his latest views on 

 the origin of the vascular bundles which plant anatomists regard as 

 being truly monarch. Apart from the mode of oi'igin, these bundles are 

 scarcely, if at all, distinguishable from collateral bundles. I do not 

 gather, from Professor Williamson's statement, whether Van Tieghem 

 was acquainted with the development of the bundles of the appen- 

 dages of Stigmaria when he pronounced them to be monarch. But 

 it may be mentioned that Count Solms, who is familiar both with 

 their structure and development, writes of them as follows ( " Fossil 

 Botany," p. 277) : — 



" That the bundles in this, as in the preceding case, are collateral 

 and capable of secondary growth, is evident at once from 

 the inspection of a transverse section figured by Williamson." 

 (Monograph of Stigmaria ficoides, pi. xi., fig. 61.) [Italics 

 mine.] 



(3.) As the authority for the more important statements made in 

 my article is given in every case, it seems both unnecessary and 

 undesirable to introduce the name of M. Renault, who is not referred 

 to in any way, and who is certainly not to be made responsible for 

 what I have written. Not less desirable is it to avoid mixing up 

 the question of the morphological nature of Stigmaria with a discussion 

 of the systematic position and affinities of the plants to which it 

 belonged. 



Thomas Hick. 



