The North American Slime-Moulds Part 37

2. AMAUROCHaeTE TUBULINA (_Alb. & Schw._) _Macbr._

PLATE XX., 6 and 6 _a_.

1805. _Stemonitis tubulina_ (Alb. & Schw.), _Cons. Fung._, p. 102.

1825. _Lachn.o.bolus cribrosus_ Fr., _Syst. Orb. Veg._, p. 14.

1912. _Amaurochaete cribrosa_ (Fr.) Macbr., _Com. in litt._ to Herbaria, Harvard, etc.[35]

1917. _Amaurochaete cribrosa_ (Fr.) Sturg., G. Lister, _Jour. Bot._, LVIII, p. 109.

Plasmodium at first transparent then white then rosy, ashen or grey finally deepening to jet-black; the aethalium even, thin, variable in extent from one to ten centimeters, covered by a distinct but thin transparent cortex, papillate, extended laterally but a short distance beyond the fructification, fragile, soon disappearing; hypothallus long-persistent, thin, silvery, supporting the capillitium as if by stipes, short slender columns, irregular plates, expansions, etc.; the capillitium an intricate network, very abundant, elastic, on fall of the peridium appearing like tiny tufts of wool, the meshes large, but formed as in _Stemonitis_, persistent, dull black; spores, under the lens, dull olivaceous black, minutely roughened, 12-14 .

This species differs from the preceding, already well known, especially in the capillitial characters. In the older species the capillitial branches fray out, and are only sparingly united into a net extremely lax. In the present form the net is the thing, common to all sporangia.

The total effect is to lend to the blown-out aethalium a woolly appearance, entirely unlike that of its congener under the same conditions. But until fructification is quite mature, the presence of the collaborating sporangia below is indicated, suggested, by the papillose upper surface.

The amaurochetes are remarkable in that they appear upon coniferous wood, logs or lumber, to all appearance undecayed. The species just described developed abundantly in August on the recently decorticated logs of _Pinus ponderosa_, on the south-western slopes of Mt. Rainier, Washington. In logging operations in the locality referred to, the trees are felled often at considerable distance from the mill. They are not infrequently large, 75-120 cm. in diameter. The logs are dragged along the ground, the transportation facilitated by removal of the bark from the new fallen trunk. In a few weeks' time, affected by alternate rain and sun, the whole surface becomes marked with hundreds of minute, almost invisible cracks, and it is in the larger of these that the plasmodium of the present species has its habitat. Hardly any mycologic phenomenon is more surprising than to see plasmodia rising to fructification, scores at a time, upon a surface, new and white, showing otherwise no evidence of any decomposition. Doubtless the persisting cambium, the unused starches, sugars, the wood of the season yet unlignified, afford easily accessible nutrition.

When this form was first examined in the laboratory its distinctness was immediately seen. It was without doubt Fries' cribrose reticularia; n.o.body questions that. Under this name, citing Fries' description, specimens were sent out to herbaria as Harvard. Further study of the records, however, soon convinces one familiar with the ontogeny of the case that we are here face to face with the species, described by Alb. & Schw. in their fine _Conspectus_. Their account of the form, evidently often taken and now described with great care, is entirely clear when read in presence of the facts. It is here submitted, as less easy of access but essential, if the reader would appreciate the present disposal of the species.

"S. Tubulina n.o.bIS

"_S. magna pulvinata subhemisphaerica, stylidiis gregariis circinantibus, capillitiis elongatis cylindraceis in ma.s.sam pulveraceam fuscam connatis, apicibus obtusis, prominulis, lucidis nigris._

"The size indeed, the circ.u.mscribed form, the capillitiums conjoined into a single body--indue this (form) with an appearance peculiar to a degree; however, should anyone prefer to call it a very remarkable variety of the preceding (_S. fasciculata_), we shall not strenuously refuse. At first glance it looks like a tubulina. After the fashion of its kind, the beginning is soft and milky. The diameter generally an inch and a half to two inches, the height four to six lines; the form perfectly round, or more rarely somewhat oblong. The hypothallus, stout, pellucid silvery, betimes iridescent, when turned to the light, easily separable from the substratum, bears the columellae, dusky, thin, hair-like, aggregate and yet entirely free, and everywhere circinately convergent, depressed by the superimposed burden, hence dec.u.mbent: ...

the capillitium loosely interwoven, coalesces to a common ma.s.s whose smooth and shining surface shows above, regularly disposed minute papillae, the apices of individual sporangia.

"Far from infrequent, on decorticate pine, of _Lycogala atrum_ a constant companion"!

It goes of course without saying, that for the authors quoted, _Lycogala atrum_ is _Amaurochaete atra_ Rost. _A. fuliginosa_ (Sow.) of more recent students, described and perfectly figured in the volume cited.

It is surprising that they did not enter the present species also as a lycogala. But the stemonitis relationship this time impressed them rather than the aethalial; besides they were misled by the _S.

fasciculata_ of Gmelin and Persoon, a composite which the genius of Fries hardly availed to disentangle twenty-five years later.

The last named author, as we see, wrote first _Lachn.o.bolus_, then _Reticularia_. He calls the interwoven capillitium--_lachne_, wool, a "_pilam tactu eximie elasticam_," etc. He read the description in the _Conspectus_, but carried away the stemonitis suggestion dominant there, as we have seen, put _S. tubulina_ A. & S. as an undeveloped phase of _S. fusca_, which, of course, it is not. It needed not the authority of Rostafinski, _Mon._, p. 197, to a.s.sure us this. The earlier authors describe the species in course of development to complete maturity, and clinch the story by declaring the form a constant companion of the commonly recognized amaurochete, so fixing the relationship for us by habitat also.

These men made a mistake, of course, in placing their species among the stemonites at all. They did much better however than Fries who called it a reticularia. It was also a mistake to cite _S. fasciculata_,--the small fasciculate tufts of _S. fusca_ and _S. axifera_ offering by the aggregate habit only faint resemblance,--a possible refuge for those who would prefer another disposition of their species distinct (_aliena_) though it is.

Since Fries' day the species has been overlooked although the genus has received more than once attention. Zukal _Hedwigia_, x.x.xV., p. 335, describes _A. speciosa_ as a new species. This Saccardo writes down, Syll. Fung., VII., p. 399, _S. tubulina_ A. & S., admitting, however, at the same time, that as fine an authority as Raciborsky refuses to call Zukal's species either a stemonite or an amaurochete, thinks it deserving generic appellation of its own.

However, _A. speciosa_ Zuk. need not here concern us. Neither in his description nor figures does Zukal at all approach the form we study.

His species is not an amaurochete; the size of the spores suggest that, to say nothing of the capillitial structure.

In the same volume VII., the distinguished author introduces another amaurochete, _A. minor_ Sacc. & Ellis, _Mich._ II., p. 566. This is American; sent from Utah by our famous pioneer collector Harkness. A specimen is before us: it is a lepidoderma! in shining, scaly armor dressed; vid. under _L. carestianum_.

Since the distribution of Washington material, as mentioned, our species reappears at various points in western Europe, points in England, etc., and will no doubt now share, hereafter as a century ago, the habitat so long conceded to the long familiar older type.

_B._ STEMONITACEae

Capillitium abundant, springing usually as dissipating branches from all parts of the columella; the sporangia generally definite and distinct, though sometimes closely placed and generally rising from a common hypothallus.

=Key to the Genera of the Stemonitaceae=

_A._ Fructification aethalioid; capillitium charged with vesicles 1. _Brefeldia_

_B._ Sporangia distinct, or nearly so.

_a._ Stipe and columella jet-black.

1. Capillitium so united as to form a surface net 2. _Stemonitis_

2. Capillitial branch-tips free 3. _Comatricha_

_b._ Stipe and columella whitish; calcareous 4. _Diachaea_

=1. Brefeldia= _Rostafinski_

1873. _Brefeldia_ Rost., _Versuch_, p. 8.

Sporangia occupying in the aethalium several layers, those of the median, and especially of the lowest layers, furnished with columellae which blend beneath; capillitium threads in the lowest layers arising from the columella, in the upper extending radiately between the individual sporangia, and united at the sporangial limits by means of rather large inflated sacs.

The genus _Brefeldia_ is, like some others, difficult to dispose of in any scheme of cla.s.sification where linear sequence must be followed.

Rostafinski placed it in an order by itself. Its relationships are on the one hand with _Amaurochaete_ and _Reticularia_, and on the other with the _Stemonitales_, though easily distinguished from either. It is intermediate to _Amaurochaete_ and _Stemonitis_, and withal, as it appears to us, a little nearer the latter, as the limits of the individual sporangia are in _Brefeldia_ pretty well defined.

1. BREFELDIA MAXIMA (_Fr._) _Rost._

PLATE V., Figs. 7, 7 _a_, 7 _b_, and PLATES XXI., XXII.

1825. _Reticularia maxima_ Fries, _Syst. Orb. Veg._, I., p. 147.

1875. _Brefeldia maxima_ (Fr.) Rost., _Versuch._, p. 8.

aethalium large, four to twenty cm, papillate above, violet-black at first, then purple or purple-brown, developed upon a widespread, silver-shining hypothallus; sporangia in favorable cases distinct, indicated above by the papillae; columellae obscure, black; capillitium abundant, the threads uniting by multifid ends to surround as with a net the peculiar vesicles; spore-ma.s.s dark violet-black, the individual spores paler by transmitted light, distinctly papillose, 12-15 .

A very remarkable species and one of the largest, rivalled by _Fuligo_ only. To be compared with _Reticularia_, which it resembles somewhat externally, and with some of the larger specimens of _Enteridium_. The plasmodium at first white with a bluish tinge is developed abundantly in rotten wood, preferably a large oak stump, and changes color as maturity comes on, much in the fashion of _Stemonitis splendens_, leaving a widespread hypothallic film to extend far around the perfected fruit-ma.s.s. In well-matured aethalia, "_Jove favente_," the sporangia stand out perfectly distinct, particularly above and around the margins.

Closely and compactly crowded, they become prismatic by mutual pressure, and attain sometimes the height of half an inch or more. In the centre of the fructification, next the hypothallus, the sporangia are very imperfectly differentiated. Many are here horizontally placed, and perhaps supplied with an imperfectly formed peridium,--if so are to be interpreted the lowest parts of the capillitial structure, the long, branching, ribbon-like strands which lie along the hypothallus. Some of these branch repeatedly with flat anastomosing branchlets, ultimately fray out into lengthened threads, and perish after all the superstructure has been blown away. From every part of the structure so described, but more especially from the margins, are given off in profusion the strange cystiferous threads, so characteristic of this genus. These are exceeding delicate filaments, attached at one end, it may be, to a princ.i.p.al branch, at the other free or united to a second which again joins a third, and so looping and branching, dividing, they form a more or less extended network, a capillitium in which are entangled the myriad spores. Each filament bears at its middle point (or is it the meeting point of two?) a peculiar plexus which embraces several large cysts or vesicles whose function or further h.o.m.ology does not readily appear.

From the base of the fructification rise also ascending branches which are black, terete, and not infrequently branched as if to form the capillitium of a stemonitis. These ascending branches are in many cases, probably in all, real, though as yet imperfectly developed, columellae.

They rise, at least in many cases, directly from the hypothallus, each is central to an individual sporangium, rises to about two-thirds its height, but never attains the summit. The sporangia are so crowded that many are choked off below, never reach the top of the aethalium. In such cases the columella may cease at the sporangium-top. The columella bears cystiferous threads sparingly, if at all; nevertheless these abound in the peripheral portions of the sporangium all the way up, and are especially noticeable beyond the level of the top of the columella. Many are so arranged that the plexus with its vesicles occupies a place in the plane separating adjacent sporangia, suggesting the possibility that we have here to do with an imperfectly developed surface-net and peridium. In this view the cysts would represent the meeting-point of two opposite radial capillitial threads rather than the middle of one.

This accords with Rostafinski's observations and drawings. The cysts, then, belong morphologically to the peridium or sporangium wall. It is a stemonitis whose sporangia have never been perfectly differentiated, a case of arrested development. See further under _Stemonitis confluens_.

Rostafinski really offers the first definitive description. Fries probably distinguished it, but his description would not indicate the fact except for the added note wherein appears the reason for discarding an apparently older name, viz., that given by Link. But neither Link nor Sowerby distinguished by description or figure _Brefeldia_ from _Amaurochaete_.

Throughout the northern forest; Maine to Vancouver Island: not common.

=2. Stemonitis= (_Gleditsch_) _Rost._