APHROSINA. 



[ 64 ] 



AP10CYSTIS. 



into two sets by a fissure on each side. 

 Thirty-nine pairs of feet, biramous ; the 

 upper branch carries the long, flexible, 

 brilliantly coloured bristles forming the silky 

 fringe on each side of the body. 



This animal is a very interesting object 

 to the microscopist, as its tissues are very 

 transparent and easily examined. 



The brilliant colours of the bristles and 

 hairs arise from iridescence, produced by a 

 number of longitudinal striae or interspaces 

 between the component fibres of which the 

 bristles and hairs consist ; they also exhibit 

 transverse splits or cracks ; they are not 

 materially changed by the action of boiling 

 solution of potash, except that the external 

 coat of the hairs becomes transversely wrin- 

 kled, giving these the appearance of being 

 surrounded by a number of fibres (PI. 49. 

 fig. 20). 



BIBL. Johnston, Ann. JV. Hist. 1839, 

 p. 430 ; Van d. Hoeven, Zool. p. 232. 



APHROSI'NA, Carter. A minute, pa- 

 rasitic, poriferous Foraminifer, with nume- 

 rous irregular, vesicular chambers. Allied 

 to Carpenteria. 



BIBL. H. J. Carter, J. Micr. S. ii. 500. 



APHTHA. A disease affecting the mu- 

 cous membrane of the mouth, tongue, &c. 

 It exhibits itself in the form of rounded 

 patches of larger or smaller size, of a whitish 

 or yellowish colour. One form of it, vul- 

 garly called the " thrush," and in French 

 niuguet, which occurs very frequently in 

 children, and in adults towards the fatal 

 termination of chronic diseases, is of special 

 interest, inasmuch as the patches consist 

 of numerous epithelial scales mixed with 

 the filaments and isolated cells of a fungus 

 (Oidium albicans). A portion examined 

 under the microscope exhibits : 1, nume- 

 rous oval cells (a, PI. 38. fig. 1), rarely con- 

 taining an internal globule or nucleus ; 2, 

 long filaments (6) exhibiting a further ad- 

 vanced stage of development ; the filaments 

 are but rarely jointed ; 3, epithelial scales, 

 sometimes perfect (d), but usually wrinkled 

 and otherwise altered in form, and fre- 

 quently more or less opaque (e), so as to be 

 hardly recognizable except when treated 

 with potash ; intermingled with these 

 bodies are sometimes vibriones or bacteria 

 (Bact. termo,f) and a molecular form of 

 matter (<?), probably an early stage of Bact. 

 termo ; for it is always found with and 

 prior to it in decomposing liquids, in addi- 

 tion to the molecular granules found in all 

 animal liquids. 



This fungus appears to arise in the same 

 manner as other analogous fungi, as those 

 in kept organic liquids, in urine, &c. ; the 

 spores are probably always floating in the 

 air and dropping from it upon all the ex- 

 posed parts of the body ; and wherever they 

 find a proper nidus, there they grow. In 

 diseases accompanying or preceding aphtha, 

 the regeneration of the oral epithelium is 

 probably to a great extent checked, the 

 secretion of the saliva also, which would 

 wash away these organisms; why they 

 occur so frequently in infants, is probably 

 owing to the saccharine nature of the diet, 

 which is especially favourable to their de- 

 velopment. 



It is to be observed of the numerous 

 parasitic Fungi which have been described 

 as preying on animal tissues, that a great 

 portion are mere conditions of common 

 species of Aspergillus, Penicillium, Mucor, 

 &c., which assume different forms according 

 to the nature of the matrix. This has not 

 been sufficiently kept in view by authors 

 unacquainted with the genera of Fungi ; and 

 in consequence, a great number of spurious 

 genera have been proposed, and considerable 

 confusion has ensued ; while the fashion of 

 late with Hallier and his followers has 

 been to confound things which are essen- 

 tially distinct. See OIDIUM. 



BIBL. C. Robin, Hist. Nat. d. V6g. Para- 

 sites, 1853, p. 488, where many other works 

 are mentioned. 



APIOCYSTIS, Nageli. A genus of Pal- 

 mellaceae (Confervoid Algae). Aquatic plants 

 parasitical upon Confervae, consisting of 

 pear-shaped or clavate vesicles from 1-50" 

 to 1-20" high, and about half as thick, at- 

 tached by the narrow extremity, and con- 

 taining numerous green primordial cells 

 about 1 -2500 to 1-3500" in diameter. Young 

 sacs contain regularly 2, 4, 8, 16, 32, &c. ; 

 and in large ones the number amounts to 

 300 to 1600. At first they lie irregularly 

 in the cavity, afterwards they lie upon the 

 wall in one or more layers ; sometimes they 

 are attached to the wall in groups of eight. 

 At a certain stage, the primordial cells be- 

 come again free in the cavity, move actively, 

 and finally escape by the rupture of the sac, 

 swarm as biciliated zoospores for a time, 

 then settle down and germinate. 



A. Brauniana (PI. 5. fig. 5) ; in ditches, 

 &c. Brit. 



BIBL. Nageli, Einz. Ah/en, p. 67, t. 2. A. 

 figs. 1 and 2 ; Henfrey, fr. Mic. Soc. 1856, 

 iv. p. 49, pi. 4 j Rob. Alg. iii. p. 43. 



