TRANSACTIONS OF THE MICROSCOPICAL SOCIETY OF LONDON. NEW SERIES. VOLUME VII. LONDON: JOHN CHURCHILL, NEW BURLINGTON STREET. 1859. FEB 12 1°53 LIBRARY \ B7e. oe “RSS wi TRANSACTIONS. On the Gerais (site and its AFFINITIES. ev By F. C. 8. Rover, F.L.8., F.G.S. (Read May 19th, 1858.) Tus genus Biddulphia, one of the most interesting of all ae the class of Diatomacez, both from the generally large size and peculiar structure of the frustules, was one of the first of the minute class of Algz that attracted the attention of microscopists. Included by the earliest observers with a heterogeneous collection of other forms, differmg widely in their structure, under the general title of Conferva, it was about fourteen years before its title to generic distinction a was recognised, and then, together with the genus Fragillaria a of Lyngbye, and the Diatoma of De Candolle, formed the —~ whole of the order Diatomidez, enumerated in the ‘ Natural .) arrangement of British Plants’ of S. F. Gray. The genus, however, as formed by this writer, included only three de species, B. pulchella, B. obliquata, and B. stipitata, which, im as more attention was given to the lower class of Algae, pond were soon found to be widely different in their organization jm and modes of growth; the first, however, has been ever since wy considered the type of the genus I am now about to de- | scribe, whilst the second formed that of the genus Isthmia Ds of Agardh, and the last was included by the same writer in the genus Achnanthes, as established by-Bory. When Ehrenberg first began to pay attention to these microscopic forms, the constant succession of memoirs read before the Berlin Academy, imduced a large number of microscopists, both here and on the Continent, to study with greater care the infinite variety and beauty of these minute plants, that had hitherto been almost unnoticed, except by a very limited number of algologists; and from that time the genus Biddulphia has attracted a large share of atten- tion. The species, however, of which it is composed, being the most protean in their habits of growth of the whole order of Diatomacez, presenting even in the same localities very great variety both in form, size, and areolation of the entire frustules, and exhibiting such totally different appear- ances when only the separated valves are examined, that it has, during the last fifteen years, been divided and sub- divided, on slight, and I think quite untenable, grounds, into about eight or nine genera, including, in the various papers of Ehrenberg, Ktitzing, Bailey, and others, nearly sixty species. VOL. VII. b i ds as a as Stud.eund ESE 2 Rover, on Biddulphia. The late Professor Smith, by extensive research and consi- derable judgment, has placed our native species of Diatoma- ceze on a tolerably sound foundation, as compared with the overloaded classification of previous observers; and by generally characteristic generic descriptions, aided by the ad- mirable figures of Mr. Tuffen West, has enabled every careful microscopic observer to study these interesting forms of life with comparative confidence. But, as the limits of his work would not permit him to enter largely into the cha- racters of any particular genus, and, at the same time, those from foreign habitats are altogether unnoticed, I pro- pose, in the present communication, to bring before the Society as complete a monograph as the means at my dis- posal will admit of the entire genus of Biddulphia, and, having referred to all the authorities, to form a synonymy which will bring it into a more intelligible form than at pre- sent exists. Professor Smith I consider has acted with sound discrimina- tion, In again uniting the genera Zygoceros, Odontella, Denti- cella, andCerataulusof Ehrenberg and Kutzing, under the head of Biddulphia; and whilst I propose to adopt the arrangement so far, as brought forward in his ‘Synopsis,’ I wish to bring before the Society my reasons for dissenting from some points in his classification, which I think it very probable he would have been inclined to modify, or partially rearrange, from evidence that has lately been discovered, had he lived to bring out another edition. The earliest notice of the genus Biddulphia is that in Smith’s ‘English Botany,’ dated in 1807, where it is alluded to, under the name of Conferva Biddulphianum, as “a curious plant, of which we find no description, found by Miss Susan Biddulph, in November or December last, at Southampton.” The figures, however, given in the plate, No. 1762, although said to be “exact copies of chosen specimens,” are drawn apparently from different plants; the upper figures alone being those of Biddulphia, and though small and rather roughly drawn, are evidently taken from specimens of B. pulchella. Dillwyn, the next writer who notices it, in his ‘ British Conferve,’ published in 1809, merely repeats the statements in the ‘ English Botany,’ but does not appear to have seen the plant, and gives no figures. Lyngbye, in his ‘Tentamen Hydrophytologize Danice,’ published in 1819— a surprising work for the extent of research and accuracy of his delineations, considering the little attention then paid to microscopic subjects, and the inferiority of his instruments to those now in use—appears not to have met with B. pulchella ; but he describes and figures, as Diatoma auritum, another Rover, on Biddulphia. 3 species of the genus, which is so exceedingly variable in form, that it has led to many of the errors which have been propounded by subsequent observers. Agardh, in his ‘Systema Algarum,’ in 1824, and afterwards in his ‘ Con- spectus Criticus Diatomaceorum,’ published in 1830, was the first who brought forward anything approaching a full classification of this tribe of plants, with an extended lst of species; but he appears to have been ignorant of the classi- fication of Gray, in his earlier work ; and though he alludes to Biddulphia in the second, the species pulchelia was unknown to him except by description, and he continues to retain it under the title of Diatoma Biddulphianum, and states that it probably may prove one of the Desmidiez. Inthe same work, however, probably from having seen specimens, he appreciates the characteristic distinction between the D. auritum of Lyngbye and the true Diatomas of De Candolle, and founded the genus Odontella for its reception. M. De Brébisson, in his ‘ Considerations sur les Diatomées,’ in 1838, having had his attention directed for some time to this class of Alge, and aided by improved instruments, was able to make a con- siderable advance on the classification of Agardh, and adopt- ing Gray’s genus of Biddulphia, with a true appreciation of specific characters, associated with it the Odontella auritum of the former writer; and the same arrangement was adopted by Mr. Ralfs, apparently from independent observa- tion, in 1843.* In this arrangement, unfortunately, these writers were not followed by other Continental observers ; Kutzing retaining the genus Odontella in his latest works; whilst Ehrenberg, having in his ‘ Infusionsthierchen’ applied that name to a species of the Desmidiez, proposed that of Denticella for the same forms. In 1839 the latter writer communicated to the Berlin Academy a paper on the marine species of Diatomacez found at Cuxhaven, in which, among other new genera, he described one, under the name of Zygoceros, to contain those species of the Biddulphian type which he considered to be free forms, and not concatenate ; but at present we have only negative evidence in support of this being a permanent distinctive character, and, as Professor Smith has observed in describing his Biddulphia rhombus, the typical species of the new genus, “ the form and structure are too near those of Biddulphia to permit its separation, and the filamentous condition of the species will no doubt reward the future explorers of the tidal harbours and estuaries of Britain.” + In 1843, Ehrenberg added another genus under the name of Cerataulus to include those species allied in form to his * ‘An. Nat. Hist.,’ vol. xii, p. 273. + ‘Synopsis,’ vol. u, p. 50, 4, Rover, on Biddulphia. genus Denticella, but which he considered nonconcatenate, in the same way that he had already separated Zygoceros from Biddulphia; but as hitherto both Biddulphia turgida and rhombus* have generally been obtained from mud deposits, and after boiling in acid, it is highly probable they will both be found, when met with in abundance in a living state, to be filamentous forms, and-therefore not entitled to any other than specific distinction. Having thus sketched the origin of the various genera into which the genus Biddulphia has been divided by Ehren- berg, I shall now proceed to Kiitzing, the most systematic of the German writers. In the arrangement of the family he chiefly follows that author, but, as I have already mentioned, retaining the name of Odontella of Agardh, for those species included in the genus Denticella; but he ignores entirely the Biddulphia pulchella of former authors, and separates it into three distinct species, naming them fri-locularis, quinqgue-locularis, and septem-locularis, the difference being merely the number of lobes into which the valves are divided, a character utterly unworthy of notice as affording specific distinction, as no gathering can be made of B. pulchella, when it’ occurs in any abundance, without meeting with frustules divided by a different number of cost, varying from three to seven. From a careful examination of the various papers referring to this genus, I find it has at various times been described under the following generic names: . Conferva, with 1 species. . Diatoma, Rar ene . Biddulphia, ,, 14 ,, »Odontella, 2-57 a0 tet . Denticella, ,, 15 . Zygoceros, .,, 18 . Cerataluiss (Sa) hcalin ae . Isthmia, ei ak .“iiceratram <3) ah eS CO™ 3 Od OF Hf CO DF 58 Rejecting altogether some of the species described by Ehrenberg from small fragments, and of which it is im- possible to form the least opinion, either from his descriptions or figures, I believe these may be reduced to about eleven good species, and together with two hitherto undescribed, as far as I know, include all the well-established forms that can be separated by good specific characters. I have already alluded to the great variation that exists in * The Cerataulus turgidus and Zygoceros rhombus of Ehrenberg. Rover, on Biddulphia. 5 the outline, size, and arrangement of the valve and connecting - membrane in the perfect frustules of this genus; and to this cause we may trace the long list of synonyms appended to nearly every species. The determination of any constant characters upon which to fix their limits as a genus is, as stated by Professor Smith, a matter of some difficulty, but they all agree in having rounded or compressed frustules, the terminal valves having submarginal processes always placed near the extremities of the long diameter when the valve is oval or approaching lanceolate in outline, always more or less reticulate in structure, generally spmous, and united by a connecting membrane often of considerable breadth, which is also reticulated in the majority of the species, and in this and the genus Amphitetras frequently projects beyond the suture of the valves when undergoing self-divison. But though the exact definition of the genus presents some difficulty, when we come to consider what is or what is not a species, upon what grounds their limits are to be defined, and the terms in which any specific characters are to be drawn up, the variations that occur in different localities, and even in any abundant gathering, are so remarkable, that the greatest uncertainty prevails, and the most discordant Opinions are entertained as to the limits that should be pre- scribed, or even upon what grounds the specific characters should be based. That Ehrenberg and Kiitzing have erred - in placing any dependence on the presence or absence of the spines on the surface of the valves, I think, is now generally admitted by all who have carefully studied the genus. ‘The number of lobes in those species in which they occur, is also subject to great variation, ranging from three to seven in B. pulchella; and if the Deniicella polymera, of which only a separated valve appears to have been seen by either Ehrenberg or Professor Bailey, is correctly referred to B. Tuomeyit of the latter author—of which, from the figure and description, I think there can be little doubt—we have in that species a variation ranging from one to thirteen lobes, each of which, if the system of Kutzing was adopted, would have to be made into a distinct and separate species. But this ground of specific character has been abandoned by Professor Smith in the first-named species, and is equally without weight in any other. The connecting membrane, again, is immediately after self-division exceedingly narrow, but increases in breadth as the frustules approach maturity, till from being barely perceptible, it frequently exceeds in breadth, and is sometimes nearly double the length of the valves themselves, before the act of self-division is again completed ; and though i in some species more or less areolate, 6 Ropsrr, on Biddulphia. the markings are by no means constant, and, in fact, no dependence whatever can be placed on its size or structure alone as a ground of specific character. On what, then, are the species to be founded? I believe that the only safe and constant characters which can be depended upon are as follows: the structure and areolation of the separated valves; the position, not the number, of the spines ; the size and form of the processes, and their position on the surface of the valve. Considering the known species with these points in view, we find them fall into two very distinct groups. The first, having B. pulchella as the type, with more or less elliptical lobed valves, having undulating margins, distinct and rounded areolations,* with the spines rising from the summits of the lobes, and processes distinctly areolate, placed at the extremi- ties of the valves ; including three species. The other, having B. aurita as the type, with valves more or less lanceolate, elliptical, or orbicular, without undulations at the margin. The areolation generally indistinct, but when otherwise hexagonal. The spines sometimes central, sometimes submarginal; and the processes only partially areolate, varying considerably in size and length, and some- times placed at some little distance from the margin of the valve. This division includes ten species. I now proceed to describe the species, slightly altermg the generic character as proposed by Professor Smith. The specific characters, where not inserted, are to be considered the same as in the ‘ Synopsis.’ Genus Bipputpuia, Gray. Frustules compressed or cylindrical, adhering more or less perfectly into a continuous or zigzag filament; valves convex, elliptical, lanceolate, or orbicular, usually spmous and areolate; areolations rounded or hexagonal, with horn-like processes rising from the angles or margin of the valve. * Professor Smith applies the term “cellules” to these markings (see Introduction to ‘Synopsis,’ vol. i, p. xvii; and again, vol. il, p. xix). He has evidently adopted this designation after much thought, and a careful comparison with other forms of cell-membrane, but the distinctive physio- logical character of a cell, that of being a completely closed vesicle, appears to me to be entirely wanting, or at least not at present shown to exist, even in those species where the markings are most obvious, such as Triceratium Javus and Biddulphia pulchella, &c. I consider that the reticulated struc- ture of the siliceous epiderm is merely adapted to strengthen the cell-wall, and therefore prefer the use of the terms, areolation or reticulation, to dis- ed ti those markings on the valves which are usually described as cells or cellules. Rover, on Biddulphia. 7 Section I.—Valves with undulating margins, and elevations separated by coste or deep constrictions. 1. Biddulphia pulchella, Gray. (‘ Synopsis,’ p. 48.) Marine ; not uncommon on the English coast, and generally distributed on the shores of Asia, Africa, and America. Syn. ConFreRva Bippuupuiana. Eng. Bot., 1807, vol. xxv, t. 1762 (upper figures); Dillwyn’s Brit. Conf., 1809, p. 52. BippuLPHIa PULCHELLA. Gray, Arr. Brit. Pl., 1821, vol. i, p. 294; Ehr. Ber. Tran., 1843, t. ii, vi, f. 18; Ralfs, Ann. N. H., 1843, t. vii, f. 3; Pritch. Inf., 1852, p. 456; Smith’s Syn., 1856, vol. ii, t. 44, 45, 46, f. 321; Mont. Fl. d’Alger., LOG. ates BippuLpHianumM. Ag. Syst. Alg., 1824, p. 5, and Consp. Crit. Diat., 1830, p. 54; Hooker’s Brit. Flor., 1833, p. 404; Harvey, Man., 1841, p. 201. DenticeLtta Bipputpuia. Ehr. Ber. Tran., 1843, t. ii, v1, f. 19; Pritch. Inf., 1852, p. 345. BIVDULPHIA TRI-LOCULARIS. Kiitz. Bac., 1844, t. xix, f. 89, and Sp. Ale, 1849, p. 137; Pritch. Inf., 1852, p. 456. BIDDULPHIA QUINQUE-LOCULARIS. Ktitz. Bac., 1844, t. xix, f. 1, and Sp. Alg, 1849, p. 187; Pritch. Inf., p. 457, BIDDULPHIA SEPTEM-LOCULARIS. Kiitz. Bac., 1844, t. xix, f. 2, and Sp. Alg., 1849, p. 138; Pritch. Inf., 1852, p. 457. BIpDULPHIA AUSTRALIS. Mont. Pl. Cel. de Cuba, 1845, p. 5. This beautiful and cosmopolitan species has been so well described by Professor Smith, Mr. Ralfs,* and others, that there is little to add as to its general structure. I may, however, remark, as corroborative of the opinion maintained by Professor Smith, that the apparent openings at the ex- tremities of the produced angles, are in fact closed by a slight siliceous membrane, that they will be found in perfect specimens to be fringed by thickened projecting points of siliceous matter, having the appearance of spines, and re- sembling in some degree the peristome of a moss. With respect to the synonymy, I am rather doubtful whether the Biddulphia australis of Montagne ought not rather to be referred to the B. Tuomeyi of Bailey. By the kind assistance of Dr. Hooker, I have been able to refer to his original descriptions, in which he says, “ Les cing cellules longitudinales qui terminent d’articule a chacune de ces extremités ne sont pas égales, et que ce sont les deux externes, et la moyenne qui saillent davantage, les imtermediares restant plus courtes ;”’+ and he states that for that reason and * «An, Nat. Hist.,’ 1 ser., vol. xu, p. 274. 7 Ramon de la Sagra, ‘ Hist. de Cuba,’ p. 5. 8 Rover, on Biddulphia. some others of minor importance, he considers it distinct from B. pulchella, of Gray. But I find in the ‘ Flore d’Algerie,’ he gives a description of B. pulchella, = there refers to his former B. australis as synonymous ;* and as Kiitzing has adopted the same view,t in the absence of figures or authentic specimens, I feel bound to follow these later opinions. The Denticella Biddulphia of Ehrenberg is clearly referable to this species, as the only distinguishing character, either in his figures or descriptions, is the presence of sete or the awl- shaped spines of Professor Smith on the central lobe, which may always be seen in perfect frustules. 2. Biddulphia regina, W. 8. (‘ Synopsis,’ p. 50.) Marine. Island of Skye, Barlee. Smith’s Syn. Brit. Diat., 1856, p. 50, t. xlvi, f. 323. This fine species, described, as far as I am aware, for the first time by Professor Smith, has not hitherto been noticed in any other locality than that above referred to, nor can I find any reference among the numerous papers of Ehrenberg, — or those of Kiitzing, or Professor Bailey, that leads me to believe they have seen a similar form. Professor Smith alludes to the possibility of its being identical with the Zygoceros Tuomeyii of Bailey, but I shall endeavour to show in discussing that species that there can be little doubt it is entitled to rank as a distinct form. 3. Biddulphia Tuomeyit, Bailey (sp.) Valve elliptical, margin undulating, usually with one or three median elevations or lobes, occasionally more, the central one always the largest, and all more or Jess spinous ; processes long, narrow, and turgid at the base; areolation circular, small, and generally in concentric lines on the lobes, finer and parallel on the connecting membrane. (PI. I, figs. 12.) Marine. Petersburg (Virginia), Piscataway, and Bermuda; Bailey. Natal; Shadbolt. Californian guano; Roper. Levant mud; Williamson. Syn. Zycocrros Tvomeyit. Bailey, 1844, Sil. Journ., vol. xlvi, t. iii, . 3, 4, 8; EH. Quekett, Lon. Phys. Journal, 1843, t. ix, f, 135 3 8; Williamson, Mem. Phil. Soc. Manch., 1848, tind fol DENTICELLA TRIDENS. Ehr. Ber. Trans., 1839, p. 73. * Mont., ‘Flore rene b p. 196. + ‘Spec. "Alg.,’ p. 137 Rorrr, on Biddulphia. 9 DENTICELLA TRIDENTATA. Ihr. Ber. Pro., 1844, p. 79. BIDDULPHIA TRIDENS. Pritch. Inf., 1852, p. 457; Hhr. Microg., Mote XX, f. Oo, b. XIX, f. ole DENTICELLA SIMPLEX. Shadbolt, Mic. Jour., 1854, t.1, f. 16. DENTICELLA MARGARITIFERA Ibid., t. i, f. 17. BIDDULPHIA TRIDENTATA. Ehr. Microg., 1856, t. xvii, f. 52, t. xxi, DENTICELLA POLYMERA. Ehr. Ber. Pro., 1844, p. 266; Bailey, Sil. Jour., 1845, t. iv, f. 20; Pritch. Inf., 1852, p. 345. ODONTELLA POLYMERA. Kiitz. Spec. Alg., 1844, p. 187. This fine and well-marked form has been found always with the same peculiar characters in so many localities, that there can be little doubt it is entitled to rank as a distinct species ; as far as I am aware, it has not yet been met with on the coasts of England, though in some respects it ap- proaches the preceding species, B. regina, of the ‘ Synopsis.’ Through the kindness of Professor Williamson, I have been able to examine authentic specimens of that species, of which the figure in Professor Smith’s volume gives a very correct representation. It differs from the form described by Professor Bailey as Zygoceros Tuomeyii, in having all the lobes and processes of nearly equal length, in the absence of the spines on the summits of the lobes, in the greater depth of the constrictions, and in the greater size and more irregular arrangement of the granular markings or reticulations. In B. Tuomeyit, the processes are long, narrow, and usually twice the length of the adjacent, and about one third longer than the central lobe; all the median elevations are spinous, and always more widely separated than in B. regina. AsI have found these peculiarities constant in specimens from various localities, as well as in the figures in Ehrenberg and elsewhere, they appear to afford sufficient ground for specific distinction. In describing this species, Professor Bailey states, that “ at the base of each of the swellings, the shell often shows perforations, and the whole surface 1s covered with shagreen- hike asperities ;”’* these markings at the base of the lobes are not perforations, but appear to arise from slight de- pressions, which are brought more prominently into view, from the greater projection of the valve at these points than at the base of the constrictions ; the same appearance is seen m-5-regine. | (See ‘ Syn.,’ t. xlvi, fig. 323.) In examining the synonymy of this species, Khrenberg’s name of Denticella tridens appears to have the priority as to date, but as it occurs not unfrequently with only one lobe, * ¢Siliman’s Journal,’ Ist series, vol. xlvi, p. 188. 10 Rover, on Biddulphia. and occasionally with ten to twelve, as shown in the Den- ticella polymera of ‘Sil. Journal,’ vol. xlvim, tab. iv, fig. 20, clearly only a large specimen of the present form, the de- signation tridens is so decidedly inapplicable, that I am in- duced to retain that of Tuomeyzi, given by Professor Bailey. I have examined a large number of specimens of the Denti- cella simplex and D. margaritifera, of Mr. Shadbolt,* from Natal, and they are clearly identical with the present species, neither the number of the lobes or the spines being suffi- cient ground for specific distinction. The most characteristic figure of this species is given by Professor Williamson, in his paper on the “ Levant Mud,” in the ‘ Memoirs of the Philosophical Society of Manchester,’ vol. vii, new series, tab.1, fig. 1; but, as that work is not generally accessible, I give a figure of a specimen from Californian guano, supplied me by my friend Mr. Ralfs. Mr. Shadbolt’s figures in the ‘Micros. Journ.,’ vol. 11, tab. 1, figs. 16, 17, are good repre- sentations of the smaller frustules, not unfrequent in the Natal gathering. Section II.—Valves lanceolate, elliptical, or orbicular, without undulating margins. 4. Biddulphia aurita, Bréb. (‘Synopsis,’ p. 49.) Marine or brackish water. A very common species on the coasts of England, and on those of Kurope, Asia, Africa, and America. Syn. Diatoma auRitum. Lyngb. Tent. Hydro. Dan., 1819, t. lxii; Hooker, B. EL, 1833, p. 404. ODONTELLA AURITA. Ag. Consp. Crit. Diat., 1830, p.56; Smith’s Eng. Bot., t. 2842, f. 2; Harv. Man., 1841, p- 201; Kutz. Bae., 1844, bres fs 88 ; Spec. Alg. , 1849, p. 136 ; ’Priteh. Infus. ss 1852, p- 470. BippvuLpuia aurita. Bréb. Cons. sur les Diat., 1838, p.12; Ralfs, Aun. Nat. Hist., vol. xu, 1843, t. vin, f. 4 Priteh, Inf, 1852, p. 456; Smith, Syn., 1856, vol. i, t. xlv, f. 319; Micros. Dict., 1856, $i SAV she 2. DENTICEELA AURITA. Ehr. Microg., 1854, t. xxxv, A, 23, f. 7... Denticrna GRacttis. Why. Ber. Acad. Pro., 1840, ioe 206, and B. Trans., 1840, p. 12; Pritch. Inf, 1859, p. 344, This species, although common in most marine gather- ings, rarely occurs in much abundance, and, like some other members of the genus, is subject to very great variations in form even in the same locality, as may be seen, by compar- ing the various figures given in the ‘ Synopsis’ of Professor Smith, whose description, together with that of Mr. Ralfs,+ *® “Micros. Journal,’ vol. il, Transactions Micros. Soc., & Fs Tt See ‘Ann, Nat. Hist.,’ vol. xl, 1843, p. 272. Rorsr, on Biddulphia. HH leave nothing to add as to its general structure. Agardh founded his genus Odontella on this species, apparently from the presence of the spines on the summit of the central infla- tion, as the only description he gives of the genus, is © Frustilla dentibus coherentia filum formantia.”* Kiitzing, both in his ‘ Bacillarien,’ and also in his later work, the ‘Species Algarum,’ retains a large number of species under that generic name. ‘The valves in this species vary consider- able in outline, and though usually elliptical-lanceolate, as stated by Professor Smith, they occasionally occur of a nearly perfect oval. (See Plate I, fig. 3.) They are, however, readily distinguishable from all others of the genus from the presence of the central elevation, with three or more spines on its summit, which is merely a circular projection of a portion of the valve, and does not extend across it, as in B. regina, nor is it separated by constrictions or cost; as is clearly shown in fig. 319 a of the ‘ Synopsis.’ 5. Biddulphia rhombus, Ehr., sp. (‘ Synopsis,’ p. 49.) Marine or brackish water. In addition to the localities ‘noticed by Professor: Smith, in the ‘ Synopsis,’ it has been found in a living state near Tenby by the Rev. J. Guillemard, in various localities in America by Professor Bailey, in the Baltic and North Sea by Ehrenberg, and at Gorleston by Col. Baddeley. (Plate I, fig. 4.) Syn. ZyGocERos RHOMBUS. Thr. Ber. Acad. Proc., 1839, p. 156, and Trans., 1840, t. iv, f. 11; Bailey, Sil. Jour., 1844, vol. xlvi, t. ii, f. 10,11; Kiitz. Bacil., 1844, t. xviii, f. 9, and Spec. Alg., p. 139; Pritchard, Inf., 1852, p. 450; Roper, Mic. Trans., £354, vol. uy, t. vi, £. 5. DENTICELLA RHOMBUS. Ihr. Ber. Ac. Proc., 1844, p. 79; Pritch. Inf., 1852, p. 345. * ODONTELLA RHOMBUS. Kiitz. Spec. Ale., 1844, p. 136. ZYGOCEROS RADIATUS. Bail. Notes, 1853, t. i, f. 29. cond 3 kHomMBUS. W. Smith, 1856, Syn., vol. 1, t. xlv and ma, t. a2: This fine species is not so common as the preceding, though it is by no means rare in the Thames. ‘The finest and most abundant collection, however, that I have seen, occurs in the clay obtained by Mr. Okeden from a brickyard near Caermarthen. I know of no foreign localities in which it has been observed, excepting those noticed by Ehrenberg in the North Sea and Baltic, and in North America by Professor Bailey. The structure of the valvesin this, as in all the following species, differs from those which * Ag. ‘Consp. Crit. Diat.,’ p. 56. 12 Rover, on Biddulphia. precede it, in having no central elevation or constriction of any kind, and is the only species, excepting B. tumida, in which there are several short submarginal spmous processes. The minute structure of the valve itself also differs from the preceding species, having the appearance of dots or puncte under a low power, but resolvable, with a one-eighth objective, into distinct hexagonal reticulations. It differs from B. granulata in the more apiculate character of the valves, in having six or more submarginal spines instead of two in the centre of the valve, and in the absence of the peculiar gra- nular structure characteristic of that species. 6. Biddulphia Baileyui, W.S. Valve imperfectly siliceous, divided into three segments by lines joming the angular processes, the central portion raised, with two slight median elevations, each armed with one or two very long awl-shaped spines; processes somewhat linear, with truncate apices; reticulation diagonal, minute. (Plate I, figs. 5 to 9.) Marine. In addition to Professor Smith’s localities—Caldy, Pembrokeshire, Rev. J. Guillemard; Humber, Norman ; Barking Creek, Roper; Gorleston, Col. Baddeley; coast of Northumberland, Dr. Donkin; Caermarthen, Okeden; Lymington Harbour, E. Grove; Mobile and Savannah, Bailey. Syn. ZyGocERos Mositensts. Bailey, 1850, Mic. Observ., t. ii, f. 34, 35 ; Pritch. Inf., 1852, p. 450. . BrpputrHia Baiterir. W. Smith, 1852, Syn., vol. ii, t. xlv, lxu, f. 322 This species differs from all others of the genus in the peculiar structure of the valve, which is angular, the central portion being raised and comparatively flat, whilst the sides are inclined at a considerable angle, the junction of the three portions appearing as slightly sigmoid or curved lines on the side view, as shown in figs. 7, 8, and 9. This species, like B. aurita, is subject to very great variation in form and size, so much so, that the specimens in one locality, without careful comparison with those from several others, might readily be considered distinct from the typical form ; but though differmg greatly in the proportionate length and breadth, in the size of the processes, and length of the spines, I feel convinced that all having the imperfectly siliceous character, and peculiar angular form of the valves, may safely be referred to the same species. The side view of the valve has not been given by Professor Smith, but it is almost Roper, on Biddulphia. 13 essential for the safe determination of the species. In some specimens the processes are short, and the spines placed not in the centre as in the normal form, but almost half way between the centre and edge of the valve. The rough outline figure, and short description given by Professor Bailey of his Zygoceros Mobilensis, leave little doubt that Professor Smith was correct in considering the present species identical with the form occuring on the American coast, and though a strict observance of the rules of nomenclature would lead to his specific name being retained, I think it better to follow Professor Smith in naming it after our lamented American microscopist. 7. Biddulphia granulata, n. sp., Roper. Valve elliptical, or elliptical-lanceolate, considerably raised in the centre, covered with fine diagonal reticulations, and interspersed with very short spines or small tubercles, at irregular intervals. Two long awl-shaped spines rise from the centre, generally bent about the middle at an obtuse angle; processes short, rather inflated at the base, and slghtly recurved. (Plate I, figs. 10, 11; Plate II, fig. 12.) Marine or brackish water. Dredged of Caldy, Rev. J. Guillemard; Barking Creek, Roper; Gorleston, Col. Bad- deley; New Brighton, Cheshire, Comber. Syn. DENTICELLA TURGIDA. KEhr., 1840, Ber. Acad. Pro., p. 207. OpoNTELLA TURGIDA. Kiitz., 1844, Bacil., t. xviil, f. 9, and Spec. Alg., p. 136 Pritch.- Inf., 1852, p. 470. DENTICELLA TUMIDA? Bailey, Soundings, 1851, t. 1, f. 57. The species here figured does not appear to have been noticed by Professor Smith, who refers to the Odontella turgida of Kiitzing as a probable variety of B. aurita,* and his figure certainly gives ground for this opinion. Had I not met with this form in more than one locality, and always preserving the same well-marked points of distinction, I should have been inclined to have concurred in this supposi- tion ; but the want of the central inflation, and the greater length, peculiar bent form and position of the spines, which are situated near the processes, and not, as in B. aurita, in the centre of the valve, together with the obtuse and generally recurved form of the processes themselves, clearly separate it from that species; whilst its more robust form, distinct granulation on the surface, inflated processes, and absence on the side view of the peculiar lines, are sufficient to distinguish * 4 : 3 F ; rs ¢ f * belie Lae Eas = J ‘ / f j it je YS ’ ‘ y =. by PTH IOWA Oh eRe AR aime del re ' , % F Pees * G ' . shui Py b: pee - j - 5 TRANSACTIONS. On a New Mernop of Micrometry.. By Wm. Sypnry GipsBons, Melbourne, Victoria. (Read Nov. 24th, 1858.) SITUATED, as I am, at so great a distance from the great centres of science, and deeming myself, in comparison with those whom I have the honour to address, as yet but a student, I feel some diffidence in submitting the results of my labours. For many matters which seem to me important may be considered trivial by those older and better skilled than myself, and what is really new to me may have been anticipated in the old country. Nevertheless, I desire to make progress myself, and to be useful, as far as I can, to others. As the object of this paper is to introduce a micrometric contrivance of my own which I believe to be new, and have found very effective, rather than to give a history of micro- metry, which would be tedious and out of place, I shall not occupy time or space by describing at length the other in- struments employed for accomplishing the same end. But it will be necessary to compare some of the modes, for a twofold purpose : first, to explain more clearly the nature of my supposed improvement; and secondly, to show that, although it has been nearly approached, it is in fact original and new. I shall, then, be as brief as possible. The micro- meters already in use may be considered as of four kinds. 1. Scales applied to the object, the divisions being arbitrary and requiring proportional calculation; of this kind were the rough measurements of Leeuwenhoek, and the more perfect scales of Lister, who placed on the stage a slip of ruled glass, the value of whose divisions was known, and viewed them in comparison with a micrometer of the second class, in order to ascertain the value of the divisions in the latter. 2. Scales applied to the eyepiece, so as to coincide with the magnified image of the object as projected into the body of the instrument by the objective, and to be viewed with it, so that the two images of scale and object were presented together to the eye. Ofthis class are Jackson’s, Ramsden’s, and the cobweb VOL. VII. e 32 GipBons, on a New Method of Micrometry. micrometers. 38. Scales of specific divisions applied to the object and viewed with it. Of this class are the ordinary glass stage micrometers, which, however, will only do for powers that are low enough to admit of the scale and object being nearly in focus at the same time; except, indeed, for very rough measurements, when the object is first viewed, and the space it occupies retained in the mind’s eye while the scale is rapidly brought into focus. 4. The projection of the magnified image: on a sheet of paper by means of the camera lucida, and ihe measurement of it by lines previously drawn upon the paper, or by the application of a determinate scale. All these methods require much previous calculation, and most of them need special adjustment and peculiar delicacy in the scales themselves, besides limiting the ob- server to the particular lenticular combinations for which they were contrived. My plan, which may be added as a fifth class to the above category, consists in the application of a previously magnified scale to the object itself, or rather to its magnified image. I had long been in the habit of using a common drawing scale or foot rule for the estimation of magnifying powers. I laid the rule on the stage, and viewed one of its divisions through the instrument, and the whole rule with the dis- engaged eye. The distance to which the magnified division extended on the normal scale was then a matter of very simple calculation, and was registered for each power. ‘The same method served also to measure the field. When I wished to measure an object, I observed it in the usual way, against the same rule viewed with the disengaged eye, and the proportion, fractionally rendered by the previously registered formula, gave the measurement. It then occurred to me (nearly two years since) that the process might be further simplified. The following extract from my note-book shows the method I employed, and the steps by which I arrived at my present plan : “‘ Lay on the stage of the microscope, beside the object, a scale of any kind sufficiently long to include the diameter of the field (a foot rule with tenths serves very well). View the object against this by the use of both eyes, one at the instrument and the other outside, the latter directed toward the rule: a little practice will render this easy. Note the measurement. Then substitute a stage micrometer for the object, and observe in like manner, so as to determine the value of its divisions relatively with those of the rule. (This, of course, need only be done once for each combination.) Gipsons, on a New Method of Micrometry. 33 A simple formula, applicable to all cases, is the result. With care, and the use of well-made scales, this process 1s as accu- rate as it 1s simple.” (These were my earlier operations, and I frequently use the same modes even now, although they have led me to a much better plan.) : “‘ By thus projecting the image of the micrometer in card, or other material, a scale may be made for each combination of lenses. The scale so made may then be laid on the stage beside the object, and viewed with it at the same time outside the instrument with the disengaged eye. The magnified image will then bear exact proportion to the enlarged scale upon which it is projected, and the measurement, which wit then be actual, may be read off, at once, to a very minute frac. tion. This process will have special advantage in the case of living objects, which may be measured even while in motion.” My mode of making these scales is as follows: I place an ordinary stage micrometer, which I keep as a standard, on the stage, and, beside it, a long slip of card, glass, or metal plate. Viewing these together, as above described, IT prick off the intersections of the micrometer divisions with a line ruled on the card, &c. I then remove the card, ink in the divisions, and subdivide them as far as may be ad- visable. This is practicable on the enlarged scale to a degree that would be confusing, even if possible, on a common mi- crometer. JI make such a scale for each combinaticn of powers, and for such positions of the draw-tube as I find convenient (2. €., as give even numbers, &c.) My first application of the plan was to one of Oberhauser’s microscopes. J made nine scales, viz., one for each combi- nation of three eyepieces and three objectives. I send here- with one of the original scales, by way of sample, as it will better illustrate my meaning than more detailed description ; of course it will be applicable to any instrument adjusted to the same number of diameters. For Oberhauser’s, the field of which does not exceed five inches diameter, and for other imstruments having small calibre, the card scales answer very well; but for my large Ross I have them on glass, as the large field, 94 inches od Gissons, on a New Method of Micrometry. diameter, requires a more rigid material. One half of the width of these glass scales 1s covered with paper so as to render it opaque, and the scale is drawn over both the trans- parent and opaque portions; thus they do not need any special light to be thrown upon them, but the divisions are visible by the diffused light, whether transmitted or re- flected. This of course is an advantage, as the image of the object is not impaired by extraneous light. The diamond. ruling will perhaps hardly be sufficient for the glass, and an opaque pigment will make the divisions more distinct; on the paper ink alone suffices. The delicacy of the process will be judged from the cir- cumstance that, in the pattern scale sent herewith, the 1-10,000th part of an inch is not only readily observable by the naked eye, but is even susceptible of subdivision ; for the eye is always capable of appreciating low fractional parts wherever it can distinguish (7. e., detect space between) two objects, such as the divisions upona scale. I have measured blood-corpuscles with these scales with as much ease, and much in the same way, as I should measure a window--pane with a common foot rule. It is, in fact, the readiest mode of applying to the magni- fied image of an object a similarly magnified image of a known scale, permanently constructed. These scales, when con- structed for given multiples of diameters, will, of course, be applicable to any instrument worked with similar powers. I would suggest to microscope-makers the advantage which would result from their sending out with their instruments scales constructed on this plan. They may be cheaply made, and would always be useful. Nothing would be easier than to print on a sheet of cardboard a series of scales, ranging progressively from 25 (say) to 1000 diameters, 7.e., scales equal in division to such multiples of the graduations whose names they bore. ‘Thus on the scale marked “100” the divi- sions marked 1-100th would be an inch in extent, and would be subdivided; and so on with the others. These might be cheaply produced, and would be always valuable. For inter- mediate powers each maker might issue scales with every instrument. Even if variation of the lenses caused them to be only approximate in the special cases, the remarkable delicacy of the process will give sufficient aceuracy for ordi- nary purposes, even after leaving a margin for error arising from want of uniformity between different sets of lenses in combination. But a person, who, being a manufacturer, re- quired a large number of such scales, could easily construct them proportionally from two or three data. Gippons, on a New Method of Micromeiry. 35 The practice of measuring magnifying powers by the double sight of a scale is not, I believe, peculiar to me, although original, and, I think, improved on by my mode; but the essential matter, viz., the construction of scales corre- sponding to the magnifying power of the combinations used, and the method of viewing such scales with the naked eye while the cbject is viewed through the instrument with the other, is absolutely my own; and I have taken some pains to assure myself that it was, as far as I could ascertain, new, before I ventured to write a paper on the subject; for of course I labour under great disadvantages in this out- of-the-way corner of the world, and must be careful that I am not hanging on behind while I fancy I am moving ahead. I am only surprised that the many persons who have laboured toward the simplification of micrometry have not hit upon this plan before, as several of them have passed very near it. My claims, to borrow for a moment the language of the Patent Office, are— 1. The application of permanent magnified scales to the magnified image of the object by the use of two eyes, one through the instrument and the other outside ; and 2. The construction of such magnified scales, corresponding to given powers, for general use. I have only to add that I hope the plans will be found as useful and satisfactory to others as they have been to me. I shall be glad to find that any makers adopt the suggestions I have thrown out, and shall be gratified by hearing from any who may undertake the production of such standard scales as I have described. [That the descriptions in the above paper of the different methods of micrometry which have been practised are not in every instance correct, the following account of Mr. Lister’s method will plainly show : He first sketched an outline of the object by means of the camera lucida; and then, without altering the arrangement of the microscope, substituted a stage micrometer, and sketched a few of its divisions. By subdividing these with compasses he formed a scale by which (both being equally magnified) the sketch of the object could be measured. The author is also in error when he states that all the 36 Mitcue tu, on a Pulsatile Muscular Organ. methods in use require much previous calculation. That none is necessary in Mr. Lister’s, either in drawing the scale or in using it, is evident; and the value of the divisions in every form of eyepiece micrometer, whether cobweb or glass, is obtained by observation, and can be so adjusted by means of a draw-tube, that the only calculation required—the multi- plying or dividing by a single figure—may in all cases be performed mentally. | _ The author’s method, however, is founded on correct prin- ciple, will give a tolerable approximation when carefully used, and can readily be adopted by observers in any “‘ out-of-the- way corner of the world.” On these grounds the Council of the Microscopical Society is recommended to give it a place in their ‘ Transactions.’ The referee does not, however, concur in the author’s esti- mate of its extreme accuracy ; which he appears to found on the minuteness to which the divisions of the scale can be carried, without considering the difficulty of observing their exact coincidence with the image of the object to be measured when the shghtest movement of the head must alter their re- lative position. : Nor would he wish the Council to reeommend instrument- makers to print scales for different magnifying powers; because the length of the body will materially affect the result, unless they are placed at the definite distance of ten inches from the eye. For an observer, situated like Mr. Gibbons, at an immense distance from any microscope-maker, this form of micrometer will form a respectable substitute, until he can procure some- thing more accurate.—Gerorcre Jackson, Referee. | On a PutsatiteE Muscurar Orean, auxiliary to the Circu- LaTIon, found in the Lues of certain Insects. By Lieut. J. MitcHe.t. (Read Dec. 22d, 1858.) Tus organ, which was found in all the legs of an insect belonging to the family Nepade, is a pulsating muscular sac, the nature of whose office is made apparent by the fact that the circulation of the blood ceases the instant its motion is interrupted. The pulsation being intermittent, these interruptions are frequent; the action continues for about ninety seconds and then ceases for about half that time. The movement of the blood-discs is always preceded by the pulsa- Mirtcue.., on a Pulsatile Muscular Organ. 37 tion of the sac. Its function therefore being that of an additional impelling organ, it may be termed an auxiliary heart. This organ, there is good reason to believe, consists of two chambers, for by altermg the focus of the microscope a double current can be observed on each side of it. These currents are distinctly seen to pass close up to it, but are then lost sight of, and their passage through it cannot be observed. This may be caused by the energy and rapidity* of the pulsa- tion, and also by the organ at each contraction being thrown into transverse ruge, which render it more opaque. At the exact instant of its coming to rest, however, a few discs may be seen within it, but these are speedily lost sight of, as is also the organ itself, for being of the same colour as the rest of the tissues of the limb, its existence can only be plainly seen while it is puckered when in action. A darkish curved line is all the indication of its existence when at rest. The organ does not occupy the same position in all the legs. In the anterior pair it is in the broadest part of the claw-like tarsi close to their junction with the tibie; it was here I first detected it. I afterwards found the same organ in the tibia, close to the knee-joint, in the second and third pairs of legs. The organ in question is found in the very young and small larve as well as in the pupa and perfect insect. In some pup, kindly furnished tome by the Honble. Walter Elhott, upwards of two inches long, the pulsating organ was so large that it could be well seen with a two-inch objective ; aud, with the one-inch, at every contraction it was seen to be thrown into the transverse folds previously men- tioned, the edges of the folds having the appearance of little cords pulling at the concave margin of the sac, which is always the most visible part of the organ. The heart appears to expand again by its own elasticity; for though one or two cords are seen to extend in a longitudinal direction, they probably do little more than keep the organ in its place. In some Notonectidz, also, after a little trouble I discovered a similar movement, but it was so much more difficult to see that it would in all probability have escaped detection had I not been specially in search of it. In a small transparent water-beetle I could not find it; neither could I detect anything like it in the larva of Agrion or of Ephemera. In the foregoing I have endeavoured to record what the * 200 per minute, measured with a metronome. 88 Mircuer.., on a Pulsatile Muscular Organ. microscope has shown me, without entering into any specula- tions; but if we sought for a reason why this insect is furnished with such an unusual organ, I think it might be found in the slow pulsation of the dorsal vessel and languid circulation in the body, rendering some additional force necessary to impel the blood to the extremity of its long and slender limbs. : [The foregoing is an abstract only of Lieut. Mitchell’s communication, which was accompanied by figures. But we have not thought it necessary to insert more than the main points in his paper, seeing that he is quite mistaken in sup- posing that he was the first to discover the curious organ he attempts to describe. It has been long well known that the circulation of the blood in the legs of certain insects is aided by the action of muscular fasciculi, situated near the articulation of the tibia with the femur. This fact was discovered by M. Behn in 1835, in the young of Notonecta; and the same condition has since been noticed in Corixva, Plea, Naucora, Nepa, and Ranatra. M. Behn conceived the organ in question to be of a special kind, whilst M. Leon Dufour conceives that the movement in question is due to the crdinary muscles of the leg. The latter observer, moreover, denies the existence of the currents described by M. Behn, and whose statement 1s now supported by the independent observations of Lieut. Mitchell. A similar phenomenon has been observed by M. Verlohren in the feet of Tettigonia and of the larvee of Ephemera, con- trary to the experience of Lieut. Mitchell. Degeer also speaks of pulsations resembling those of an artery in the legs of a species of Ornithomyia. M. Behn describes the double current noticed by Lieut. Mitchell as running in opposite directions on the two sides of the limb; and states that the movements of these currents coincide with those of the pulsatile organ, and are apparently independent of the contractions of the dorsal vessel. It will thus be seen that, although the phenomenon has been long well known, there are still some disputed points connected with it. For this reason, and because the subject is one of considerable: interest, and perhaps not familiar to many microscopical observers, we have thought right to publish the sum of Lieut. Mitchell’s brief communication, with the above comments; for the greater part of which we are in- debted to a note in the third volume, p. 226, of M. Milne Edwards’s invaluable ‘ Lectures on Physiology.’—Ens. | 39 A MicroscoricaLt Inquiry into the VEGETABLE PARASITES infesting the Human Sxin. By Janez Hoce, M.R.C.S.E., &c. (Read Jan. 26th, 1859.) AN investigation into the many peculiarities which sur- round parasitic growths, and their rapid development and increase, is one that may be expected to repay the micro- scopist for any amount of time he may bestow upon them, and we find, indeed, as much to imterest and instruct us, in ” this the lowest department of vegetable life, as in that of the highest. The microscope shows us that all the fungi have seed-vessels bearing fruit a hundred or a thousand fold, and that there is scarcely a spot of earth on which this fruit in the shape of minute spores cannot be found. Insoluble in nature, they wait, where they fall, the growth and decay of the particular plant for which each has its affinity ; so that the enemy is near to the very soil from which it is to draw life. These spores, so imponderable, float about in the air we breathe, seeking a nidus in everything, be it vegetable or animal. In the latter, whenever the healthy processes of nutrition are impaired, and the incessant changes between the solids and the fluids slacken, the human skin then fur- nishes a rich and proper soil for these spores to take root in and germinate. I have lately been engaged in a micro- scopical examination of the products of the cutaneous surface, for the purpose of ascertaining what share the parasitic growths take in the production of certain well-known forms of skin disease, and to decide, if possible, whether they are directly and solely the cause of disease and disorganization of the epidermal structures; or whether, from a decline of the general health, or some constitutional predisposition, the parasitic vegetation is the result of disease? For the elucidation of my subject, I have made in all up- wards of eighty examinations of the products of skin dis- eases, taken from patients under my friend Mr. Hunt’s care at the Western Dispensary for Diseases of the Skin. The products have been examined wet and dry, with reflected and transmitted lght, under a power of from 200 to 400 diameters, and every means taken to avoid error. The spe- cimens have been obtained in scaly and papulous diseases by gently removing the half-detached scales; in moist eruptions, by simply placing the discharge on a slip of glass ; in diseases of the hairy scalp and beard, by uprooting the hairs and ex- amining them immediately. The sketches were made at the same time simply with a view to a faithful portraiture of what 40 Hoge, on Parasitic Fungi. was seen, without any reference to artificial classification on the one hand, or to pathological theory on the other; and careful drawings have been made from my sketches by Mr. Arthur Hunt to illustrate this paper. The cases examined are distributed among fourteen genera of Willan’s classifica- tion of cutaneous diseases, namely, in Porrigo, Psoriasis, Pityriasis, Sycosis, Lepra, Lupus, Lichen, Impetigo, Furun- culus, Eczema, Vitiligo, Spilus, Ichthyosis, and Acne. The filaments or spores of a cryptogamic plant were found in all the genera excepting Impetigo, Furunculus, Vitiligo, and Acne, and, I think, we must add Lupus, in which genera the examinations happen to have been few in number. In four distinct diseases arranged under three of these genera, viz., Ist, Porrigo decalvans, or Tinea decalvans, or Alopecia cir- cumscripta ; 2d, Porrigo scutulata, or, Tinea tonsurans, or, Herpes tonsurans ; 3d, Pityriasis versicolor, or P. lutea or Cloasma ; 4th, Sycosis or Mentagra: in these forms fungi had been seen by previous observers, as also in Porrigo favosa ; but in the other six diseases, viz., Psoriasis, Lepra, Lichen, Eczema, Spilus, and Ichthyosis, no author had reported any observations of the kind: and so certainly have these dis- eases been considered free from vegetations, that they have not been included with the five above-named diseases, and on which the name Dermatophyta has been bestowed. ‘There are probably reasons why the parasite should not so fre- quently be met with in these seven diseases; but I have, nevertheless, found them in the instances related, although not in all those examined, as the following record will show. ANALYSIS OF CASES. At the head of my list I placed Favus, but this disease is so rarely seen, either at the Dispensary for Diseases of the Skin, or in private practice, that I have not been fortunate enough to obtain a specimen for examination. Although so ‘rare here, it appears to be particularly well known on the Continent, and, consequently, has received much attention. Schoenlein was the first to describe the vegetable character of the favi, and to make a drawing of the filaments and granu- lated stroma; this fungus is, therefore, called after its disco- verer, Achorion Schoenleinii. Gruby described more accu- rately its mycelium and spores. We are told by them that Favus is frequently followed or accompanied by Pity- riasis, Eczema, and Impetigo, and is therefore lable to be confounded with the fungus of Trichophyton tonsurans, from which it is to be distinguished by observing the difference in Hoge, on Parasitic Fung. 41 form and size of the spores and mycelium. The spores of the Achorion Schoenleinit are oval and comparatively large, whilst those of Trichophyton tonsurans are spherical and small. M. Gruby gives the following directions for making examinations of the products of Favus, and which answers for the examination of other skin diseases. He says, in order to examine the natural position of these fungi microscopically in the animal cutaneous structures, it 1s necessary to make a thin section of the capsule completely through, embracing the outward layer of epidermis, amorphous mass, and hght friable matter found in the centre. It will then be found, on pressing this slightly between glasses, and examining it with a magnifying power of 300 diameters, that the cylin- drical tubes (¢halli) spring from the sides of the capsule, proceed inwards, give off branches dichotomously, which, when fully developed, contain at their terminations (mycelia) a greater or less number of round or oval globules (speridia). These tubes are from the y3>5th to =},5th of a millimetre in thickness, jointed at irregular intervals, and often contain molecules, varying from ,55455th to z)55th of a millimetre in diameter. The longitudinal diameter of the sporules is generally from 53,th to 745th, and the transverse about the same (Gruby). The mycelia and sporules agglomerated in masses are always more abundant and highly developed in the centre of the crust. The thalli on the other hand are more numerous near the external layer. There may frequently be seen swellings on the sides of the jomted tubes, which are apparently commencing ramifica- tions. Onexamining the hairs which pass through the favus crusts, it will often be found that they present their healthy structure; at other times, however, they evidently contain long, jointed branches, similar to those in the crust, running in the long axis of the hair, which is exceedingly brittle. I have generally found these abundant in chronic cases; and on adding water, the fluid may be seen running into these tubes by imbibition. There can be very little doubt that the tubes and sporules, after a time, completely fill up the hair- follicle, and from thence enter the hair, causing atrophy of the bulb and the baldness which follows the disease.* i PoRRIGO DECALVANS. Syn. Tinea decalvans, Alopecia circumscripta. The fungus known by the name of Microsporon Audcuini, is said to cause this disease, and the light-gray crusts which _* Dr. Bennett’s ‘Principles and Practice of Medicine,’ p. 801, 2d edition. 42 Tloge, on Parasitic Iungt. cover the places deprived of hair consist of the parasite mixed with a certain quantity of epithelial scales. Case 1.—The hair near the bulb. Mycelia and filaments running along its surface, as in Pl. IV, fig. 1. Case 2.—Baldness of portions of the scalp and whiskers. Parts examined, hair-bulbs and crust from the cheek. Fun- goid filaments with masses of epithelial scales; portions of hairs were covered with filaments lying on the epithelial masses. Case 3.—Circumscribed Alopecia of the scalp. Hair with mycelia growing and protruding from the sides, the hair itself filled with a blackish-brown colouring matter. Case 4.—Alopecia of nearly the whole scalp. The few straggling hairs which were pulled off the scalp presented no bulb, but were distorted and broken stumpily ; tufts of spores were grouped on the external surface of the hair. Case 5.—Complete Alopecia of the scalp, eyebrows, and eyelashes, except a few straggling hairs on the scalp. Bulb and hairs entirely deficient of their animal matter, the whole depolarizing light; sporules and broken filaments scattered about (fig. 2). Case 6.—Circumscribed bald patches on occiput and be- hind the ears. Hair-bulb rugged, and hair uneven and devoid of central medullary matter; strie and all marking on the surface obliterated and covered with spores and fila- ments. Case 7.—Alopecia circumscripta. Bald patches on the scalp, the remaining hair growing in profusion. First examination.—Bulb rugged and covered with a fila- mentous growth standing out with a dark, well-defined outline; central pulp absent, and transverse markings oblite- rated. Second examination (after three months’ constitutional treatment).—Appearance improved; striz distinctly seen, and medullary matter or pulp in a great measure restored ; no filaments or spores visible. i Case 8.—Alopecia circumscripta. Three bald patches; hair generally long and profuse; bulb broken and rugged ; no vegetative growth visible. Case 9.—Alopecia syphilitica. Hair with a_ peculiar socket-like insertion; and there is seen projecting from the root and running upwards, a casing of very transparent epi- thelium; this is divided into two portions a short distance from the root. Case 10.—Mr. M—. Bald spots with gray patches. Hairs bent and deprived of their medullary matter; a sheathing of Hoae, on Parasitic Fungi. 43 epithelium surrounds the broken hair about one fourth of its length. Case 11.—Alopecia circumscripta. Mycelia filaments and spores projecting ruggedly from the edges of dirty brown hair; filamentous masses very fine, drying up, and spores also; a peculiar branch of mycelium, with lance-like termi- nation, from one of the hairs. So that in eight cases there was most decided evidence of — fungoid growth, finding in them filaments and spores. In three cases, one of which was the product of syphilis, no fungoid growth was found. The hair from the margin of the bald spots was taken for examination in most instances. Porrico scutuLata (Trichophyton tonsurans). Syn. Tinea tonsurans, Herpes tonsurans, Ringworm of the scalp. Case 1.—Ringworm taken at school. Character: patches of the scalp covered with minute vesicles, the discharge from which had dried into thin crusts; hair on these patches thin, light, and friable, and very scanty, being broken off short, and standing out abruptly from the skin. A fine fungoid growth was visible, the mycelia and filaments branch- ing off very beautifully; a hair was seen covered with black- ish fungi; epithelial scales abundant (fig. 3). Case 2.—Ringworm. This child was sister to the above, and her scalp presented similar appearances. Epithelium thickened and running along the hair like a pyramid; ves- tiges of vegetative growth. Case 3.—Ringworm. Filaments and spores over hairs, with peculiar bulbous protuberances. Case 4.—Ringworm. Fvngi shooting from the root of the hair; epithelial scales with filaments. Case 5.—Ringworm. A remarkable twisting and diseased condition of the hairs, with numerous ovoid spores, but no filamentous growth seen. Case 6.—Ringworm. Hairs matted together, and project- ing from them mycelia filaments, and sporules separated and distributed; a chain of sporules projecting from a hair, as seen in cases of Plica polonica given by Kiichenmeister. Case 7.—Ringworm after dropsy. Hypertrophied epithe- lial scales glued together; the bulbous portion of the hair is also covered with adherent scales, upon which mycelia fila- ments and sporvles are freely distributed; chains of sporules as in former (fig. 4). Case 8.—-Ringworm. Branched fungoid filaments and a few sporules visible. 4 Hoae, on Parasitic Fungi. Case 9.—Ringworm. Hairs contorted or split up mto fine tow-like masses, over the surfaces of which spores were freely distributed ; epithelial scales detached and filled with granular matter. In nine cases of Porrigo scutulata the hair was examined ; fungoid vegetations or vestiges of them, sometimes with spo- rules, sometimes without, were observable in each of these cases; but in three of them they were imperfectly seen. It may here be observed that the filaments of the Micro- sporon tonsurans, said to be the cause of this disease, are de- scribed as found in the substance of the roots of the hair, and spreading longitudinally upwards; whereas, the Microsporon Audcuini, the supposed source of the Porrigo decalvans, forms a tube round each hair outside the follicles, not in the’ substance of the hair. I have not been able to verify these distinctions; on the contrary, on comparing many specimens of these diseases with each other, I have always found filaments springing up from the bulb, and then growing up around or along the hair, sometimes longitudinally in bifurcating branches nearly straight, sometimes in tortuous or spiral forms, with or without spores, as the drawings here exhibited will show. In both diseases the bulbs of the hairs and the hair itself- were variously decayed and deformed. - PrryRIASIS VERSICOLOR. Cloasma, furfuraceous Desquamation. Case 1.—Mr. N—. Patches about the trunk of a yel- lowish-brown appearance, consisting of a delicate desquama- tion of the epidermis. Mycelia with filaments and sporules growing and detached. Epithelial scales large. Case 2.—Microsporon furfur. As represented in drawing, mycilia, filaments with spores in groups and clustered (fig. 5). Case 3.—Epithelial scales and filaments. Case 4.—Microsporon furfur. Case 5. ; Fig. 18. Severally showing the Microsporon Case 6. Case 7. furfur. Case 8.—Fungoid vegetation. Epithelium deficient of nucleus and pale in colour. Case 9.—Filaments branching above the masses of scaly epithelium. | Case 10.—Fungi in filaments and a few spores. Case 11.—Microsporon furfur. Mycelia with filaments ne Hoge, on Parasitic Fungi. 45 _and spores in groups, granular matter, and epithelium; spores covering the epithelial scales, which were shrivelled. Case 12. Case 13. Case 14. Case 15. Case 16. Case 17. Seventeen cases of this disease contributed specimens for examination, in all of which vegetations were observed, and in several of them the fungus named Microsporon furfur, supposed to be the cause of the disease, was clearly identified. This fungus is said to have been discovered by Eichstadt in 1846, and is described as exhibiting spores piled up in groups or heaps; and, although Robin himself could not find this parasite, I acknowledge that the characteristic grouping of the spores has been distinctly marked in most of the speci- mens I have examined. But, although this piling up of the spores may be in some measure identified with the disease, it does not follow that the disease is caused by the fungus, which may merely find in this form of disease a suitable soil for its growth and fructification. The fungus may be destroyed ‘by soaking the skin witha nitrous acid or mercurial lotion, but unless attention is paid to the state of the blood no lotions will cure the disease. Severally showmg Microsporon furfur. Microsporon MENTAGRAPHYTES. Mentagra, ‘Syn.,’ Sycosis menti, 'Tubercular or pustular eruption on chin and bearded parts. Case 1.—Hairs broken and bent, covered by epithelial scales forming protuberances in the hair; mycelia covering the surface, filaments detached and sporules distributed about. Epithelial scales large, with well-marked nuclei (fig. 6). — Case 2.—Mycelia surrounding hair-bulb, sporules scattered, ‘ovoid, and some much elongated; root broken off and covered with mycelia and worn-out epithelial scales, small in size. Case 3.—Mycelia with filaments and spores were found on the hair, which had a good deal of colouring matter. ‘The enlargement of the bulb of one was remarkable, giving it the appearance represented in fig. 12. The eruption in Sycosis is peculiar, the pustules and epithe- lial scales run together in irregular patches over the face and scalp. This disease is thought to be produced by the fungus Microsporon mentagraphytes. According to Gruby it forms a kind of sheath surrounding and protecting that part of 46 - Hose, on Parasitic Fungi. the hair whichis imbedded in the skin, and whose spores are never produced above the surface of theskin. A sanious- looking matter is discharged from the pustules, which under the microscope consists of scrofulous pus-corpuscles and irre- gular blood-discs, having many more of the white blood-cells than in the blood of health. The hairs were examined in six cases of Mentagra, all were broken or bent and covered by fungoid growths. The roots of the hairs were closely invested with spores and filaments, sprouting longitudinally outwards and upwards. Both the filaments and spores are described as larger than those of the Microsporon furfur, and are said to form a sort of vegetable sheath to the hair below the skin only. This latter description is graphic and true; but I should hesitate to admit that the mere size of a vegetation can entitle it to be considered a separate species ; for it may depend on the age, the growth, or on some peculiarity of the soil, just as the Polypodium jilix-mas, or common male fern, may appear in a dry, barren soil, as a delicate plant, and yet, in a damp and shaded situation, with a congenial soil, it may assume the appearance of a gigantic shrub several feet in height. Moreover, the hair, as well as the follicles and root, was found, in several instances, with tufts of fungi growing on the surface. Psoriasis (Scaly disease). Psoriasis and Lepra are two names for one and the same disease, the former being used by authors when the scaly patches are irregularly diffused, and the other term applied when the patches are isolated and circumscribed, with ele- vated edges, denoting a more active though less extensive. form of disease. Case 1.—Cobweb-like appearances of mycelia and _fila- ments. Epithelial cells treated with Liq. Potassz exhibit a reticulated character. Case 8.—Psoriasis guttata. Mycelia with filaments in a fine hair-like state, separated and running wider over a mass: of epithelium scales. Case 9.—Nearly cured when examined. Mycelia fila- ments loose, and scattered sporules; epithelial scales with granular matter (fig. 7). Case 10.—Scales, sporules, and a few filaments. Case 11.—Psoriasis guttata. Mycelia filaments and nu- merous scattered sporangie. Case 12.—Mycelia and filaments branched. Case 13.— Epithelial scales and filaments. Hoge, on Parasitic Fungi. 47 Thirteen cases were examined, in seven of which filaments and spores were clearly discernible, in the others epithelial scales only were found. These filaments and sporules were in no respect distinguishable from those found in the various diseases already described, and to which they have been said to be peculiar. LEPRA. _ Case 1.—Epithelial scales, surrounded by a growth some- what doubtful. Case 2.—Epithelial scales only. Case 3.—Brownish-red ovoid clusters of sporules, with a filamentous growth, jointed, and epithelial scales. Case 4.—Ovoid spores, jointed filaments, and a beautiful mass of granular matter with numerous sporules. Case 5.—Mycelia filaments, jointed, with sporules. Epi- thelial scales (fig. 8). _ Case 6.—Masses of filamentous matter and detached epi- thelial scales. Case 7.—Mycelia filaments and sporules, with epithelial scales. _ _ In seven specimens examined I found mycelia filaments, and spores in five of them, and in two epithelial scales only. These fungoid vegetations were very similar to those found in Psoriasis, no doubt identical with it. IcHTHYOSIS. Case 1.—The disease in this case was a congenital hyper- trophy of the epidermis without any other indication of disease. The appearances presented under the microscope were large epithelial scales, massed and blended without a marked separation, the whole intermingled with filaments ; showing that a congenital disease or malformation may, under certain conditions, prepare a soil for fungoid growth. LicHEN. _ Case 1.—Neck and scalp. Disintegrated epithelial scales, mycelia filaments and sporules, reddish-brown, covering the hair (fig. 10). Case 2.—Scales only. _ Case 3.—Epithelium in abundance, with mycelia with a few spores. Case 4.—Filaments with spores, and epithelial scales. So that, in three cases out of the four examined, evidences. VOL, VII. 48 Hoge, on Parasitic Fungi. of fungoid growth were visible, similar in character to those already described, and very much resembling the fungus of Mentagra. Eczema (Vesicular eruption). Case |.—Kiczema leproides. Thickened and worn-out epi- thelial scales, matted together ; likewise perfect epithelium, reddish-brown ; small and very numerous fungi. Case 2.—Eczema auricule. Masses of mycelia, with fila- ments and sporules. Case 3.—Eczema of general surface. Cast of a fine hair, consisting of filaments, surmounted by epithelial scales (fig. 9). Case 4.—Eczema leproides. Hypertrophied epithelial scales only ; nuclei and nucleoli well marked. Case 5.—Mycelia branching from a broken portion of hair, with sporules distributed over the same. In four out of six cases, fungoid appearances were ob- servable ; in one of them the spores were in masses or heaps, and in another a cast of a hair was noticed, the hair having escaped, and the cast made up of a beautiful reticulation of filaments, which had previously encircled the hair, precisely after the manner of that described in Porrigo decalvans ; yet there was no baldness here; in fact the arm, and not the scalp, was the seat of the disease. Tinea—tarsi frequently appears as an eruptive skin disease about the head, face, and other parts of the body. Seven cases were taken from the eyelids (two were associated with eczema of the scalp), in four of which were found mycelia, with filaments and spores of a rounded form, mixed with a few accidental fat-cells, epithelial scales, and granular matter. In two I discovered isolated spores of the fungus, de- scribed by Ardsten as the Puccinia favi, which are almost, if not quite, identical with the spores of a fungus caught in the air. It is a remarkable and curious circumstance to find the spores of fungi penetrating to the interior of the body, and there committing ravages which are even more destructive to organic life than when they alight on the cutaneous sur- faces. It is related by Hannover, of a patient who had been a long time troubled with figures as of a string of pearls before his eye, and upon the operation of parasection bemg performed for the relief of distressing symptoms, a fluid escaped in which was found a branched mass of small Hoge, on Parasitic Fungi. A9 cylinders, partly filled with globules, and partly covered with minute cylindrical processes. The fungus, which occupied the entire of the interior of the eye, was nearly colourless, and consisted of fine and coarse fibres, with clear and uniform contents. Other fibres, more numerous, were moniliform, with granular contents. There were also many free glo- bules (sporidia), which refracted the light strongly; these bodies resembled the cells of the ferment fungus of beer, but were without nuclei. The most ternal masses consisted of free sporidia, and some fibres with the appearance of rows of globules. Hannover believes that, prior to the establish- ment of the disease which led to the destruction of this eye, there must have been the introduction of a spore of the plants through some portion of its external coat. Helmbrecht relates another case, of aclergyman who came under his care for an inflammation in both eyes, after the cessation of which he had a constant movement of some body in the left eye, and muscz volitantes in the right; the latter got well, while the object in the former remained, and, after a fall from his carriage, the figure became free. Helmbrecht now made a puncture in the lower part of the junction of the cornea and sclerotic. A fluid escaped, in which was found a branched mass, consisting of confervoid cells and rows of spores.* SPILUS. In the two following cases the moles were not congenital, but growing larger every month. Case 1.—Dark-brown moles about the clavicular and cervical regions, prominent, adherent, increasing. Hairs with peculiar masses of pigment surrounding the shaft of the hair in tufts, with granular matter. Case 2.—Female child. Numerous moles on shoulders, axille, groims, &c.; dark coloured, prominent, rapidly growing. Very fine filaments, of a dark fungoid growth, covering the surface of masses of epithelial scales. A few spores scattered about. Impetigo AND FuRUNCULUS. These diseases, as far as ] have been able to examine them, exhibited nothing but scrofulous-looking pus-corpuscles, with epithelial scales, and are properly described as :— “*Pustules with an elevation of the cuticle, with an inflamed * Dr. Kiichenmeister’s ‘Animal and Vegetable Parasites.’ Sydenham Society, 1857. ‘Translated by Dr. Lankester. 50 Hoge, on Parasitic Fungt. base, containing pus.’ They are distinguishable by being more prominent and convex, with a yellow centre, the skin being reddened all around. Pressure will cause them to discharge their contents, which appear to be degenerated or imperfect pus-corpuscles with epithelial scales. VITILIGO. Epithelial masses of scales held together by a watery exu- dation, with a few black or brownish masses. Lupus. Lupus exedens (Lupus with phagedenic ulceration). Case 1.—Altered epithelium, serum and pus-corpuscles. Fungoid growth, old, and of so dark and marked a cha- racter, as to lead to the belief that it must have been an accidental deposit of recent date. Case 2.— Large epithelial scales, with many highly refract- ing irregular granules of fat. Case 3.—First examination.—Epithelial scales; small cells; fat-globules, refracting light, principally egg-shaped ; and accidental starch-grains. Second examination.—Aggregated mass of epithelial scales, held together by some pale yellowish-brown fluid; oil- globules, slightly tinged with the yellow discharge; minute ovoid bodies; fungoid sporules. Third examination.—Fatty matter, with a little fibro- cellular tissue. ~ Case 4.—Submaxillary region. Epithelial scales aggluti- nated together by pus- and blood-corpuscles; the pus recent, and showing the characteristic nuclei upon the addition of acetic acid. Also fat- and nest-cells. Case 5.—Epithelium large and misshapen, apparently covered with fungoid filaments; fat-corpuscles in con- siderable quantities, and granular matter. Case 6.—KEHpithelium ovoid and broken up; struma or scrofulous pus, with fibro-plastic tissue and large masses a fatty matter ; hypertrophy of the epithelial scales. Case 7.—Pus exuding, small fat-globules, scrofulous pus- corpuscles, and epithelial scales. Case 8.—Fat-globules, well marked, and in large quan- tities; scrofulous pus-corpuscles with larger cells, having smaller enclosed ; epithelium large and hypertrophied. Lupus non exedens (Lupus without ulceration). Case _1.—Fat-globules, irregular in form, with eae scales very large, and pus-corpuscles. Hoae, on Parasitic Fungi. 51 Case 2.—Fat-corpuscles, large, but irregular in form; granular matter with hypertrophied epithelial scales,* broken and pale (greasy stain on the paper containing the spe- cimen); probably in this case some greasy application had been used. Case 3.—Fat-corpuscles, irregular and disorganized, large and mixed with granular matter; pus- -corpuscles ; epithe- lium broken and interwoven with fibrous tissue. The pus-corpuscles in Lupus have essentially the scrofu- lous character, with a thin, whey-like fluid intermixed with granular matter; the pus is irregular in form, containing granules which are peculiar; and from the relatively large proportion of fat in every specimen examined, it appears to be associated with degeneration of the fat-vesicle; which is constantly throwing off its contents. All the surrounding structures are implicated, and share in the disintegration and destruction of tissue. “These microscopic discoveries explain,” says Kuchen- meister, page 144 (Dr. Lankester’s translation), “not only the pertinacity of the disease—since it is well known that the lowest plants develop themselves most intensely and rapidly in a favorable medium—but also its contagious character, which is no longer doubtful. The fungus itself is the sole cause of these changes of the hair, and of the secondary irritation and congestion of the skin, which cause exudation, an accelerated formation of the epidermis, scaling off and production of crust, because the swollen hair exerts pressure on the skin.” From the results of the examinations just given, I must submit that I have drawn conclusions the very opposite to those of Kiichenmeister, and am most decidedly of opinion that the vegetation found on the skin and hair is not we marily the cause, but rather the result of disease. I shall now endeavour to show on what grounds these con- clusions are deducible : Ist. If there be any exceptions to the general law, that parasites select the subjects of debility and decay, such ex- ceptions are not found among vegetations belonging to the order fungi, which invariably derive their nutriment from matter only in a state of lowered vitality, passing into de- composition, or wherein decomposition has already proceeded to some extent. 2d. That the growth of these fungi is not necessarily pathognomonic of a special disease, is Obvious from the fact of their having been observed in nearly all kinds of chronic skin diseases. 52 Hoge, on Parasitic Fungi. 3d. Competent observers have not been able to find them in the diseases they are believed to engender. Thus Mal- herbe, Cazenauve, and Wilson deny the existence of a vege- table fungus in Porrigo scutulata (common ringworm), al- though this is described and depicted under the name of Tricophyton tonsurans by trustworthy observers. Cazenauve, Didot, and Wilson deny the existence of the Achorion Schoenleini in Favus, or cupped ringworm. Wilson and Cazenauve deny the existence of the Microsporon Audouini in Porrigo decalvans. In reference to the state- ment of the latter observer (Cazenauve) it must be borne in mind that he candidly acknowledges his ignorance of the microscope ; and not to make an unfair use of these nega- tive arguments, I must confess that I have seldom been dis- appointed in finding some kind of fungoid growth im all the diseases supposed to be produced by them; nevertheless, such is the similarity of form and growth in the specimens examined, that I have failed to make out an identity between the variety of parasite and the disease whose name it bears. Thus, in a case of Porrigo in a girl of sixteen, which had existed for nine years, from neglect and dirt, I found the fungus (fig. 11) described by Robin and Kuchenmeister as peculiar to Plica polonica, a disease almost unknown in this country. In the cases related of Tinea tarsi, I found sporules of the fungus described by Ardsten as the Puccinia favi. Robin also found in Favus the Puccinia occurring together with the Achorion Schoenleinii, the latter presenting itself as a constituent of the cups or crusts, while the Puccinia occurs afterwards on the desquamation of the epidermis; and this is thought by some to warrant the opinion that the Achorion is only the spermagonial form of the Puccinia favi. Again, it is broadly asserted by others, that the several morbid con- ditions are mutually convertible; and that Lichen, Eczema, Impetigo, Psoriasis, Lepra, Mentagra, &c., are but modifica- tions of one and the same disease, resulting from accidental conditions, and not always found perfectly distinct; nay, so often are they combined and complicated, that dermato- logists have assigned special names indicative of their mixed character, such as Eczema impetiginodes, Eczema leproides, Lichen urticatus, Erythema papulatum, &c. It may be said that most of the cases examined by Mr. Hunt and myself should be referred to the latter forms of disease, and that the finding of parasitic fungi might have been & priori expected; in short, ought to have been found by us: but keeping in view this contingency, Mr. Hunt Hoae, on Parasiiic Fung. 53 carefully selected well-marked cases only for microscopical examination. Lastly, as to the growth of these parasites on the healthy skin; most conclusive experiments have been made, which go far to prove that the skin of persons in health and vigour does not afford the required conditions for their taking root in it; that inoculation succeeds in those places only where pustules have previously formed. Remak and others tried the experiment of inoculation over and over again, but found it always failed in the healthy; yet im certain exudations or peculiar states of the constitution, or where disintegrated matters existed, and which had undergone particular che- mical changes, the Achorion may be made to germinate and produce growths of these identical fungi. Remak took the spores of fresh scabs, and found he could grow them on slices of apple. After twenty-four hours, the sporidia exhibited short, pale, homogeneous, cylindrical growths, which became larger and more transparent during the following interval. Small oval cavities were observed on the third and fourth days on the outgrowths, not sepa- rated by partition-walls, which increased in size; and on the sixth day a luxuriant growth of the Penicillum glaucum, or other species of mould, entirely covered the Favus fungus ; and further observation could not be made. Perhaps their development was arrested by the decomposition of the masses of fungi, owing to the chemical alteration of the soil. The spores of the Favus fungus germinate in solutions of sugar, but produce only thallus threads; the sporidia are formed when it is exposed to the action of the atmosphere. The mass of scabs crumbles in distilled water without ger- minating. The spores do not germinate in blood serum, or the solution of the white of egg, or in animal fats; but this was speedily effected when sugar was added, or a solution poured over either of them, when mildew grew rapidly over the Achorion, just as other mould spores quickly germinate on decaying fruits, &c. These experiments closely connect and identify these fungi with the vegetable-growing species, and from which they do not appear to me to differ in their most essential characteristics. Seeing then that the fungi are characterised throughout nature by feeding on effete or decayed matter, that the fungi supposed to be peculiar to certain diseases of the skin are also found in many other diseases of the cutaneous surface, that competent observers have not been able to find them in these peculiar diseases, that sporules and filaments described as the cause of one specific disease have been found in the products of another definite disease inferred to have a 54 Hoge, on Parasitic Fungi. parasite of its own, differing from this and peculiar to itself, and lastly, seeing that attempts have been made in vain to implant these parasites to a healthy skin—one cannot but conclude that the whole theory is erroneous, and that para- sites peculiar to and productive of special diseases do not exist. In this opinion we are at least confirmed by the therapeutical fact, that the alleged parasitical affections are rarely, if ever, cured by destroying the parasite; but by the due administra- tion of alteratives and tonics, capable of correcting the blood dyscrasia, which in fact originates the disease, they most assuredly can be cured. These views are countenanced by distinguished pathologists. Professor Bennett, writing of Favus, says, “I believe that the pathology of Favus is best understood by considering it essentially to be a form of abnormal nutrition, with exudation of a matter analogous to, if not identical with, that of tubercle, which constitutes a soil for the germination of cryptogamic plants, the presence of which is pathognomonic of the disease. Hence is explained the frequency of its occurrence in scrofu- lous persons, and among cachectic or ill-fed children; the impossibility of the disease in healthy tissues, or the necessity for there being scaly, pustular, or vesicular eruptions on the integuments previous to contagion. And in some few ex- periments wherein it has been said that inoculation has succeeded in healthy persons, the following explanation may be offered :—that the material in which the vegetations grow may, at the commencement, in a molecular exudation, be formed either primarily or secondarily, i.e. there may be want of vital power from the first, as occurs in scrofulous cases, or there may have been a production of cell-forms, such as those of pus or epidermis, which, when disintegrated, and reduced to a like molecular and granular material, secondarily constitute the necessary ground from which the parasite derives its nourishment, and in which it grows.’’* Very nearly the same conclusions have been arrived at with regard to the propagation of the moulds among the vegetable tribes, which at one time it was said originated by fungi. Mr. Henfrey, writing of the development and progress of vine fungus, says “that it is the cause, and not a consequence of the murrain ;” nevertheless, with some caution and suspicion of the truth, he adds, “there are various curious circum- stances connected with it not at all understood, and it is very probable that peculiar atmospheric conditions induce predis- posing states of the plants.” It scarcely admits of a doubt, that all the diseases observed * Bennett’s ‘Principles and Practice of Medicine,’ p. 307. Hoae, on Parasitic Fungi. bo of late years on plants have been caused by a peculiar at- mospheric condition not yet perhaps quite understood, but which, when combined with want of vigour, or, mm other words, unhealthy growth, arising from the loss of some che- mical element in the soil necessary to health, has been pro- ductive of the various “ murrains” of which we have heard so much. A fact well known to microscopists is, that, during heavy, moist, and other unpleasant atmospheric conditions, the spores of various fungi can be caught by merely exposing a slip of glass in a current of air—but when the atmosphere is fine and dry, a state usually recognised as bracing and favorable to health and life, fungi and their spores are very difficult to collect, and probably are not then floating about. Similar causes may, doubtless, affect the microscopic cha- racters of the products found in skin diseases, and so similar in appearance are the fungi taken in the air to those found among plants and decaying vegetable matter, that with a power of two or three hundred diameters we detect a striking analogy between them. The