186 EDWARD C. JEFFREY ON 



cales is phyllosiphonic, and that of the Lycopodiales, on the other liand, is oladosiphonic. 

 The writer has reached the conchision, for reasons indicated above, tliat tlie Equisetales 

 are hkewisc chadosiphonic. Assuming that the occurrence of cladosiphony in tlie two 

 groups is jjrima facie evidence of their relationship, it is necessary to add to this a number 

 of other features of similarity before it can be considered as proved tliat the Lycopodiales 

 and Equisetales are really somewhat closely allied. 



Goebel (Bot. zeit., 1887) and Buchtien {oj}. clt., p. 42) have both noticed the striking 

 resemblance between the green gametophyte of Lyco2)odiimi innndatum and L. cernmnn 

 and that of the genus Equisetum ; there are, in both cases, the same upright fleshy axis 

 and the same characteristically numerous lateral lobes. Goebel (oj). cit.) has noticed too 

 that the archegonia of L. inundatum have the same relation to tlie lol)es of the prothallus 

 as tliose of Equisetum. The archegonia of Equisetum and Lycopodium are, moreover, 

 alike, in that in both genera they are uniformly without the Ijasal cell, which is found 

 without exception in the archegonia of all the isosporous FiUcales. 



The antherozoids of the two groups differ in structure, those of the Lycopods beino- 

 liiciliate and moss-like, those of the Equisetaceae, on the other hand, being spiral and mul- 

 ticiliate. The embryo of Eqidsettmi hiemale, as has been indicated in the earlier part of 

 this essay, resembles that of Lycopodium in that root and shoot both originate from the 

 upper (epibasal) region. But the resemblances are strongest in the sporophytic i^hases. 

 Both groups are palingenetically microphyllous and have invarialily strobiloid fructifica- 

 tions. In hoth these features they present a very marked contrast to the Filicales. 

 Finally, both cohorts present the phenomenon of cladosiphonj', and in this feature also are 

 contrasted to the phyllosiphonic Filicales. 



It may accordingly be assumed, if numerous features of resemblance are trustworthy 

 indications of relationship, that the Equisetales in the larger sense indicated above 

 and the Lycopodiales are closely allied, as indeed has already been suggested by Scott 

 (Pres. address Brit, assoc, 1896, p. 15) in connection with the genus Sphenophyllum. 



Conclusions. 



The conclusions of this research may be stated as follows: — 



1. The writer's investigation of the development of the vascular axis of the stem 

 of the young plant, in a large number of representative vascular cryptogams and 

 phanerogams, has led to the recognition of two primitive types of vascular axes viz., 

 the protostelic type consisting primarily of a single concentric bundle in the sense 

 of De Bary, and the siphonostelic type, in which the vascular tissues from the very 

 outset form a bundle-tube. Of siphonostelic axes there are again two types viz., phyl- 



