iqiq] BASSLER—SPORANGIOPHOKIC LEPIDOPHYTE 95 



in old plants, "materially strengthens the anatomical analogy" 

 (Scott 28). Concerm'ng the relationship of the last remaining 

 order of the Lepidophytes Scott states: ''Recent discoveries 

 appear to show conclusively that Selaginella had no direct connec- 

 tion with the Lepidodendrae, but sprang from a distinct and 

 equally ancient herbaceous stock. No light has yet been thrown 

 on the ancestry of Lycopodium, which certainly had no near relation 

 to any Paleozoic forms in which the nature of the spores has been 

 determined." The facts presented in this paper in no wise call 

 for a revision of these conclusions. Already in the Paleozoic there 

 were forms of heterosporous Lycopods agreeing closely with Selagi- 

 nella of the present day, and although there has been specialization 

 along different lines during descent, the lowly habit of the members 

 of this group appears to have kept them so much out of competition 

 with the more aggressive arborescent forms that there has been in 

 all probabiHty but little amphlication or reduction throughout 

 this great lapse of time, and together with Lycopodium they may 

 perhaps be looked upon as something of a "persistent primitive 

 type" (Huxley). 



In 1909 Lady Isabel Browne estimated the prevailing theories 

 of Lycopodian descent as follows: 



The weakest part of the theory that the Lycopod sporangium is the result 

 of coalescence and fusion of free sporangia lies in the fact that it is among the 

 heterosporous forms {Lepidostrobus Mazocarpon, Mazocarpon, Isoetes), pre- 

 sumably less primitive than the homosporous tj^pes, that what are regarded 

 as the remains of a septum are most strongly developed. On the whole, the 

 sterile tissue present in the above mentioned forms is much in excess of that 

 found in Spencer ites* or in most species of Lycopodimn. Similarly, on Bower's 

 hypothesis that the sporangia of the synangia of the homosporous Psilotaceae 

 represent the loculi of a septate sporangium, it is curious that indications of 

 intermediate stages in the process of septation should be more marked in 

 several heterosporous than in any homosporous members of the Lycopodiales. 



The significance of these difficulties regarding the prevailing 

 theories of Lycopodian descent becomes apparent with the proposi- 

 tion that the Lycopodiales, the Lepidodendrales, and the Psilotales 



■i We are inclined to believe with W^atson (33, p. 391) that Spencerites, although 

 it may have certain archaic characters, in reality is not primitive and may not even 

 be homosporous, for as yet we have had no means of knowing that the spores are 

 not indeed microspores. 



