204 PTFFERENTIATION AND SPECIFICITY OF STARCHES. 



dark stripes on tho narrow side Those grains are usually symmetrical on all sides, although the 

 two sides of the margin sometimes develop unequally. This type passes over into the centric- 

 spherical as well as into the centric-oval type. It is found with certainty only in spores and seeds. 

 Although round grains which have been pressed together do occur in the underground parts of the 

 plant, the absence of a hilum and of lamellae makes their structure doubtful. Compound grains are 

 never or very rarely found along with the simple ones. 



(Edogonium landsboroughii Hass., Kutz. (Algce.) Dry spores. — Grains rounded, triangular with 

 roimded corners, or oval, frequently irregular; compressed to about one-half or more of the 

 width, with a longitudinal slit on the narrow aspect. Size about 12;u. Similar or somewhat 

 smaller starch-grains sometimes form a partial or complete wall within the vegetative cells. 

 Some grains approach the centric-oval (type 3). 



(Edogonium vesicatum Vauch., Link. (Algce.) Dry spores. — Grains rounded or rounded-oval, fre- 

 quently somewhat angular or irregular; the wider ones compressed to a little more than 

 one-half of their width. Size about 8ju. The more starch the less oil present. 



(Edogonium echinospermum A. Braun. (Algce.) Dry spores. — Grains as in preceding. Size about l/x. 



Bulbochoete sphcerocarpa A. Braun. {Algce.) Dry spores. — Grains circular to oval, frequently some- 

 what angular or irregular; the larger ones compressed to about one-half or more of their Viddth, 

 with a long sht on the narrow aspect. Size about 10 to 13^. Approaching the centric-oval 

 (type 3). The grains in the cell are almost equal in size and are arranged close together in a 

 single layer along the primordial sheath, within which the lumen is filled with red oil, but 

 very often it is not visible until part of the oil has been expressed. Similar grains, but some- 

 what smaller in size, often form a partial or complete wall within the vegetative cell. 



Bulbochcete setigera Roth. (Algce.) Dry spores. — Grains rounded, mostly polygonal; the larger 

 ones compressed to about one-half or more of their width; spindle-shaped when seen from 

 the narrow aspect. Size about ll/z. 



Nilella. (Characece.) Spores. — Grains roimded, usually irregularly angulai-, the angles sometimes 

 appearing almost lobular; seldom regularly 4 to 6 sided or compressed to about one-half to 

 one-third of their width; rarely with delicate lamellae, and a central hilum; di-y, without fis- 

 sures. The grains in a spore are, as a rule, of equal size, and arranged in a simple layer within 

 the inner sxirface of the membrane, and so crowded that by pressure they become i)olygonal. 



Nitella syncarpa Kutz. Fresh. — Size about 70ai. 



Nitella flexilis Ag. Dry. — Size 17 to 50-GO/i. 



Nitella fasciculata A. Braun. Dry. — Size about 14 to 56At. 



Nitella hyalina Kutz. Dry. — Size about 15 to 45/i. The fissures, which are seen from both aspects, 

 are imdoubtedly due to pressure. 



Nitella iranslucens Pers. Dry. — Size about 7 to 40;u. 



Nitella hatrachosperma A. Braun. Dry. — Size 10 to 45/i. 



Nitella tenuissima Kutz. Dry. — Size about 13 to 42;u. 



Nitella gracilis Ag. Dry. — Size about 10 to 40/i. 



Nitella exilis A. Braun.; N. Jlabellata Kutz. Dry. — Size about 15 to 45jli. 



Chara. (Alga;.) Spores. — These contain a wall of starch which consists of two kinds of grains — 

 large, rounded and compressed grains, and small grains of indistinct structure (type 10). 

 The larger grains are arranged Avith their broad side along the wall, and form a simple layer, 

 while the smaller grains fill in the spaces between the larger ones. On crushing the spore 

 the oil within comes out first, then the small starch-grains. Increased pressure will finally 

 release and expel the larger grains. For this reason the latter very often are injured, and 

 have a number of more or less marked fissures radiating from the center. In order to obtain 

 them uninjured it is best to cut the spores. 



Chara fcelida A. Braun. Fresh. — Grains rounded, at times somewhat irregular; thickness two-thirds 

 their width; lamellai numerous, usually 3 of them very distinct at regular intervals; hilum 

 large, circular when seen on one side, and elliptical on the other. Size about G5/i. 



Chara hispida Limi. Dry. — Grains almost round, rounded-oval, often exactly circular, com- 

 pressed to about one-half or more of the width; when seen from the narrow side oval, fre- 

 quently with a longitudinal slit; lamella; nmnerous, very delicate; hilum circular, when seen 

 from the broad aspect, but elongated from the narrow aspect. Size about 80 to IOO/j- 



