AMPHISTOMA. 



[ 31 ] 



AMYLOID. 



4. A. Kutzingii, Breb. {Vitreai^), Sm.) 



5. A. paludosa, Sm. 



BiBL. Ehr. Abhandl. d. Berl. Akad. 1841, 

 p. 333 ; Kiitzing, Bacill. p. 107 ; Spec. Alg. 

 p. 93 ; Smith, Brit. Diat. i. p. 43. 



AMPHISTOMA {Holostomum, Diplodis- 

 cus). — A genus of Entozoa of the family 

 Treraatoda. 



Char. Body soft, oval, cylindrical or co- 

 nical; two pores, one anterior, the other 

 posterior. 



Rudolphi enumerates 21 species, of which 

 3 are doubtful. They are most common in 

 birds, but sometimes occur in mammalia, 

 reptiles and fishes ; generally inhabiting the 

 alimentary canal ; length from 1-lOth to 

 4-5ths of an inch. 



BiBL, See Entozoa. 



AMPHITETRAS, Ehr.— A genus of Dia- 

 tomaceae. 



Char. Frustules cubiform, connected with 

 each other by one of the angles, and thus 

 forming a chain or filament ; filament at- 

 tached by a short stipes ; marine. Side view 

 of the frustules rectangular, the angles some- 

 times produced ; valves covered with de- 

 pressions, which are readily seen under a low 

 power. 



This genus approaches Isthmia and Bid- 

 dulphia, from which it difi'ers in its rectan- 

 gular and not compressed figm-e. Species : — 



1. A. ant ediluviana{F\. 12. ^g.9). Lutei'&l 

 sm-faces of the frustules with concentric ra- 

 diating depressions, their sides concave ; 

 British : a, frustules united ; b, side view ; 

 c, front \dew ; d, perspective view. 



2. A. adriatica. Depressions concentric 

 and radiating; angles of the frustules ob- 

 tuse; lateral surfaces of frustules with 

 straight sides ; Adriatic sea. 



3. A.parallela. Depressions parallel ; in 

 Greek marl. 



BiBL. Ralfs, Ann. Nat. Hist. 1843, xii. 

 p. 2/5; Kiitzing, Bacill. p. 135; Sp. Alg. 

 p. 133 ; Ehrenberg, Abh. d. Berl. Akad. 

 1839, pp. 122, 142; Ber. d. Berl. Akad. 1840, 

 p. 62. 



AMPHORA, Ehr.— A genus of Diato- 

 maceae. 



Char. Frustules solitary, free or adherent; 

 valves with a nodule (aperture ?) or a stauros, 

 at the middle of the margin on one side. 



The nodules exist on the flat side of the 

 frustules ; the frustules are plano-convex ; 

 PI. 12. fig. 10 « represents a transverse sec- 

 tion ; the side view of the frustules can only 

 be seen when these are made to roll over, by 

 sliding the glass cover upon the slide with 



the mounted needle. (Introduction, p. 

 xxii.) 



The valves are furnished with transverse 

 striae, resolvable into dots, but in some spe- 

 cies they are excessively minute. 



The species are both marine and aquatic. 

 British species : — 



1. A.ovalis,^. Aquatic; frustules turgid, 

 oval, ends rounded or truncate ; length 

 1-400"; common (PI. 12. fig. 10, front 

 view; 10 « represents a transverse section). 



2. A. miniitissima, S. Aquatic, adherent 

 to other Diatomaceae ; valves with a stam*os ; 

 length 1-1200". 



3. A. cosfata, S, Marine; ends beaked; 

 valves longitudinally ribbed ; length 1-500". 



4. A. lineolata, Ehr, and K. 



5. A. membranacea, S. (PL 10. fig. 11). 



6. A. coffeceformis, K. 



7. A. affinis, K. 



8. A. hyalina, K. 



Kiitzing enumerates 13 other foreign spe- 

 cies : — A. libyca, veneta, elliptica, aponina, 

 gracilis, ostrearia, quadrata, navicularis, 

 acutiuscula, borealis, carinata, crystallina, 

 and fasciata. 



BiBL. Kiitz. Bacill. p. 107; Sjjec. Alg. 

 p. 93; Smith, Brit. Diat. i. p. 19. 



AMYLIDE CELL, of Kiitzing. See 

 Primordial L^tricle. 



AMYLOID. — The name was given by 

 Schleiden and Yogel to a peculiar modifica- 

 tion of vegetable substance met with in the 

 thickening layers of the cell-walls, in the coty- 

 ledons of certain Leguminosae, viz. Scholia 

 speciosa, S. latifolia, Hymencea Covrbaril, 

 Mucuna urens, M.gigantea, and the tamarind 

 {Tamarindus indica); also of the common 

 white Haricot bean. When in a dry condi- 

 tion, it is of a soft horny consistence ; when 

 wetted, it softens, becomes gelatinous and 

 transparent; it is soluble in boiling water, 

 strong acids, and in solution of potash, but 

 not in alcohol or aether. It is coloured blue 

 by iodine, like starch, the compound being 

 soluble in water with change to a 3ellow co- 

 lour. The ' amorphous starch,' described by 

 Schleiden, in the seeds of Cardamomum mi- 

 nus, in the rhizomes of Carex arenaria and 

 Sarsaparilla, seems scarcely distinct from 

 amyloid ; it forms a thick viscous layer 

 lining the cells. Amyloid forms a trans- 

 itional substance between starch and bassorin 

 and cellulose, and probably presents modifi- 

 cations approaching more nearly to one or 

 other of them in different plants. 



When cellulose is treated with a mixture 

 of 4 parts of sulphuric acid and 1 of water. 



