32 West & West . — Observations on the Conjugatae . 
That this mucus is often of a tough nature is proved by 
a consideration of the genus Spondylosium , in which the 
individuals are united into long filaments by a layer of 
mucus between the apposed ends of the cells ; and that 
the connexion is by no means a weak one is shown when the 
filament is fractured, the cells more often breaking across 
the isthmus than coming apart at the apical attachment. 
Organs for attacimjent are occasionally developed in young 
plants of Spirogyra x (Fig. 20) and Mougeotia (Fig. 16), but 
have not been noticed in any other genus of Conjugatae; 
they are special outgrowths (simple or branched) at the base 
of the shoot, and are homologous to those organs of attach- 
ments found amongst other Algae and usually termed rhizoids , 
but more recently known as haptera. We have also noticed 
them to be developed in Spirogyra , as a result of the modi- 
fication of a conjugating-tube protruded by a cell some distance 
removed from those cells of the filament engaged in conjuga- 
tion (Fig. 21). 
Branching amongst members of the Conjugatae is ab- 
normal and of somewhat rare occurrence. When present 
in the Zygnemaceae it is generally limited to lateral out- 
growths consisting of a few cells ; we have only noticed it 
in the genera Zygnema 1 2 and Mougeotia (Figs. 17-19). In the 
Desmidieae one semi-cell occasionally undergoes a partial 
lateral 3 or dichotomous 4 branching (Fig. 40). 
The apical cells of filamentous Zygnemaceae are generally 
rounded at the free end, but they often become elongate and 
irregular. 
The filamentous forms consist of but one series of cells, 
longitudinal septa rarely making their appearance ; they have 
1 Borge, Ueber die Rhizoidenbildung einig. fadenform. Chloroph., Upsala, 
Nya Tidnings Aktieb., Tr. 1894. Wolle, Freshw. Alg. U. S., PI. CXLII, 
f. 7, 8. 
2 Cf. Zygnema fiachydermum, West, Alg. from W. Indies, Jonrn. Linn. Soc. 
Bot., Vol. xxx, PI. XIII, Figs. 12-15. 
3 Reinsch, Contrib. Alg. et Fung., T. xviii, f. 12 and 15. 
4 Jacobsen in Journ. de Botanique, Copenhague, 1874, t. viii, f. 31. 
