56 ON THE SPIRAL MARKINGS IN THE GENUS TRICHIA. 
the former, rings and spirals at the same time, with the addition 
of bladder-like swellings or beads towards the extremities. In 
T'richia abietina the spiral branches, and after two or three volu- 
tions becomes simple again, then running in a horizontal direction 
so as to form imperfect rings, and then again becoming oblique, 
exactly after the fashion of the mixed vessels of Pheenogams. Such 
phases, it is clear, could never be presented by any twisting of a 
flat thread, even where there is one spiral alone—not to mention 
the fact that the threads are, from their earliest growth, not flat, 
but cylindrieal—mueh less where the threads themselves are 
branched and, at the same time, irregular in outline, as is fre 
quently the case. Till a thin vertical slice from a thread can be 
obtained, it may be impossible to say, so positively as to convince 
all gainsayers, notwithstanding the deeper tint, whether there is 
really any deposit in the inside of the threads corresponding to 
the spiral markings, though in any case the elevations are due 
simply to some action within, which takes place in a spiral or 
cireular direction, passing occasionally from the one into the other. 
I have examined Mr. Knight’s specimens, prepared precisely 
according to his directions, and with an object-glass of + I see, 
clearly enough to satisfy myself, that there is a depression in the 
membrane of the thread between each spiral, exactly as the 
structure is figured by Wigand, and, indeed, previously by Mr. 
Currey*, though, at the same time, it seems clear to me that 
there is no twisting of the thread, and that the appearance could 
never have been brought about by mere torsion. In Batarrea I 
have seen the vessels more closely approaching the type in Phe- 
nogams; and, unless I am greatly deceived, I have on former 
occasions, in individuals of Zrichia which had just passed from the 
milky stage, seen nearer approaches to this than any which are 
figured in Wigand's plates. Be this, however, as it may, whether 
the difference be greater or less, it is pretty certain that the spiral 
marking of the threads is a case rather of affinity than analogy; 
and we cannot entirely deny the existence of spiral vessels in 
fungi, though they may exhibit a somewhat different type from 
that to which we are accustomed. I have seen precisely the same 
arcuate elevation in the cells of Sphagnum, respecting the spiral 
threads of which I believe there is no doubt. 
* Quarterly Journal of Microscopical Science, vol. iii. pl. 2. fig. 4- 
