228 NEMATOGENZ. 
Nostoe piscinale, Wittr. & Nord, Alg. Exs. No. 195. 
Nostoc intricatum, Meneg. Nost. Ital. p. 122. Borzi Alghe 
Fico. p. 283. 
In ditches (slightly brackish). 
“Forming small roundish gelatinous masses, floating amongst different 
species of Lemna in fresh water, but probably within the influence of the 
tide, and also amongst Enteromorpha intestinalis, and even within the 
frond in brackish water. The plant is at first of an olive yellow gradually 
assuming a greener tint, and when dried of a deep verdigris. Very 
gelatinous, delicately branched, the branches very flaccid. Under a high 
magnifier the whole plant is evidently composed of gelatine, in the centre of 
which runs a single moniliform filament, following the ramifications, and 
in its progress curling to and fro repeatedly across the thread, the joints 
bein: nearly globular. The specimens from the interior of Enteromorpha 
are paler, and have longer joints amongst the globular ones.” —Berkeley. 
Plate LXXXIX. fig. 1. Nostoc Linkia (intricata) nat. size, after 
Berkeley. 
Fig. 2. Nostoc completely developed, composed of the interlacings of 
a single trichome X 350. 
Fig. 3. Portion of trichome, spores arrived at complete maturity X 650. 
Fig. 4. u, spore commencing to germinate ; 4, c, d, e, spores in 
germination more or less advanced X 650. 
Fig. 5. Germinating filament changed into a hormogone X 650. 
Fig. 6. Free hormogone X 650. : 
Fig. 7. Motile trichomes segmenting in fragments, of which each 
constitutes a hormogone. 
Fig. 8. Immovable hormogone commencing to develope X 640. 
Fig. 9. Development of hormogones X 650. 
Fig. 10. Group of spores germinating X 350. 
Fig. 11. Chaplets of spores obtained by cultivation in germination X 
650. Figs 2 to 11. After Bornet. 
Nostoc piscinale. Kutz. Tab. Phyc. w., t. 11, f. 3. 
Fronds attached or free swimming, bullate and tuberculate, 
verdigris green, rarely rufescent, becoming olivaceous by age. 
Trichomes loosely interwoven, joints equal in diameter, rather 
distant. Spores subglobose. 
Sizz.—Joints -0037--004 mm., heterocysts ‘006 mm., spores 
‘007 x :008 mm. 
Born. & Thuret Notes Alg. ii, 90. 
Nostoc lacustre, Kutz. Tab. Phye. ii., t. 11,f.2. Rabh. Alg. 
Eur. ii., 179. Borzi Alghe Fico. p. 281. 
Nostoc agglutinans, Kutz. Tab. Phye. ii., t. 10, f.1. Rabb. 
Alg. Eur. ii., 178. 
In ditches. 
Plate LXXXIX. fig. 12. Trichomes of N. piscinale x 400; fig. 13, 
portion of trichome with heterocyst x 600; fig. 14, spores in course of 
development, with mature spores X 600; fig. 15, spores in the early 
stages of germination x 600, 
