1908] JEFFREY—FOLIAR GAPS 249 
Equisetum’? carries less weight on account of his lack of first-hand 
familiarity with the extinct members of the Equisetales, a necessary 
basis for the discussion of a group which has its history so largely 
in the past. His first objection is that the vascular system of Equise- 
tum is, on the basis of growing point development, of cortical origin 
and consequently cannot belong to the central cylinder, a term which 
in this case, according to Professor CAMPBELL, must be restricted to 
the pith, since it alone takes its origin from the sacrosanct region of the 
plerome. — It is perhaps too late to discuss conclusions ‘drawn from 
growing point morphology; they often lead rather to a reductio ad 
absurdum than to any useful or logical results. Professor Bower has 
set a very good example in his recent book in throwing the growing 
point theory and the octant theory overboard."’ Professor CAMPBELL 
sees no reason why there should be an attempt to reduce the vascular 
system of Equisetales to either of the types found in the other phyla 
of the pteridophytes. He further adds that the equisetal series 
Presents resemblances which “indicate a real although extremely 
remote relationship with the lower ferns,” thus committing the very 
error he previously condemned. Professor CAMPBELL also attaches 
4 good deal of importance to the presence of multiciliate antherozoids 
as an indication of affinities, and regards this feature both in the 
Equisetales and Isoetaceae as indicative of filicinean affinities. His 
Views in both instances ‘are at variance with those of modern paleo- 
botanists, 
It will be well in our discussion of the Equisetales to begin with 
the living genus and thence go backward, for only in the living form 
'S It possible to study the anatomical relations with necessary com- 
Pleteness. The reproductive axis of Equisetum will also afford a 
_ Petter starting-point than the vegetative, since it is a well-established 
Principle of the new morphology that the reproductive structures are 
Se likely to retain ancestral characters than the vegetative ones. 
Fig. 3 shows a longitudinal section through one of the fibrov: 
Strands of the cone of Equisetum telemateia, at a region where a trace 
'S being given off to a sporophyll. It will be noticed that the sporo- 
Phyll trace passing off on the left of the figure goes outward and 
*? Affinities of the genus Equisetum. Amer. Nat. 39:273-285- 1995: 
*S Origin of a land flora, chaps. 14 and 42. 
