OSCILLATORIACEJS. [ 561 ] OSCILLATORIACE^. 



Hassall, Ah/. 244, pis. 70-72 ; Kiitz. Sp. Alg. 

 237; Tab. Phyc. Bd. i. pis. 38-44 ; Rabenh. 

 Alg. ii. 95 ; Engelmann, Beweg. Bot. Zeit. 

 1879. 



OSCILLATORIA'CE.E. A family of 

 Confervoid Algae, containing organisms of 

 considerable diversity and not well cha- 

 racterized at present, owing to the obscurity 

 of the reproduction. The genus Oscillatoria, 

 with its nearest allies, is composed of 

 cylindrical filaments of protoplasmic sub- 

 stance, invested by a continuous cellulose 

 sheath or tubular cell-membrane. The in- 

 ternal (solid ?) filament gradually becomes 

 transversely striated as it increases in age, 

 and subsequently breaks across at the trans- 

 verse lines ; and the fragments readily 

 escape from the sheaths, since no cross walls 

 of cellulose are produced (PL 8. fig. 8). These 

 kinds exhibit clearly the remarkable motion 

 from which the family takes its name. They 

 are mostly found upon damp ground, form- 

 ing wide and irregular strata. Rivularia and 

 the allied genera have the joints of the fila- 

 ments more distinct j and the filaments are 

 coherent into definite fronds, on which they 

 stand erect or radiate from a centre (PI. 8. 

 figs. 13, 16). The sheaths often become 

 complicated, from the internal multiplica- 

 tion and the persistence of the cellulose 

 sheaths of several generations one within 

 another (see PETALONEMA), often gelati- 

 nously swollen up, and sometimes decomposed 

 into spiral fibrous structures (PI. 8. fig. 15 ; 

 see SPIRAL STRUCTURES). Some of the 

 remaining forms differ considerably from 

 the above, and are imperfectly understood. 

 Spirulind (PI. 7. fig. 15) has the filaments 

 curled spirally; and in the strange plant 

 Didymolidix (PI. 1. fig. 10) two spiral fila- 

 ments occur twined together. These last 

 minute forms generally occur imbedded in a 

 gelatinous stratum. 



The structure of the Oscillatoriaceae, 

 judging from Oscillatoria, Mi&'ocoleus, and 

 Lynybya, differs importantly from that 

 of all other Confervoids. The filaments are 

 not composed of rows of cells, but, in the 

 earliest condition, of a cylindrical thread of 

 ^protoplasm, coloured greyish, green, brown, 

 s or purple in different cases. The ends of 

 the growing filaments are narrower and de- 

 void of striae, and have no perceptible cellu- 

 lose sheath ; when a little older, cross striae 

 appear, consisting of double rows of granules 

 or dots, and the tubular cellulose coat is i 

 evident; finally the striae become distinct 

 lines (see PI. 8. figs. 8-22). In this stage, | 



external violence will cause the filament to 

 break across at the strise ; and the fragments 

 then slide along inside the cellulose sheath, 

 the broken ends always assuming a rounded 

 form like that of the free extremities (PI. 8. 

 fig. 8b). When these fragments slide quite 

 out of the sheaths, the latter appear as con- 

 tinuous tubes (PI. 8. fig. 8 a), seldom with 

 any cross markings opposite the strife of the 

 internal mass. In Lynybya the division 

 seems to take place in a peculiar manner, 

 accompanied by an interstitial growth com- 

 parable to that of ZYGNEMA. In a well- 

 developed filament, every eighth stria is 

 strongest, the intermediate fourths rather 

 lighter, every second one between them 

 paler still, and the intermediates of these 

 only just marked; while in Oscillatoria the 

 striae seem to be gradually less definite 

 towards the growing apex of a filament. 

 The filaments appear solid as ordinarily 

 viewed ; but the endosmose resulting from 

 placing them in syrup or gum- water causes 

 them to contract between the stria?, or to 

 break up into lenticular disks. The ultimate 

 fate of all the filaments seems to be a sepa- 

 ration into disks or globular gonidia, by 

 breaking across at the striae. 



In Microcoleus (PI. 8. fig. 9) and many 

 Rivularice there would appear to be a trans- 

 verse multiplication like that occurring oc- 

 casionally in NOSTOC, as the filaments are 

 found lying side by side in gelatinously de- 

 composed outer (parent) sheaths. The fila- 

 ments of the Rwularice are seated on a 

 large basal cell (PL 8. figs. 13, 16, 18), the 

 nature of which is not understood. 



The remarkable spontaneous motion of 

 many Oscillatoriaceae presents a considerable 

 variety of conditions. In Oscillatoria and 

 Microcoleus the ends of the filaments emerge 

 from their sheaths, the young extremities 

 being apparently devoid of this coat ,- their 

 ends wave backwards and forwards, some- 

 what as the fore part of the bodies of cer- 

 tain caterpillars are waved when they stand 

 on their prolegs with the head reared up. 

 This motion probably depends upon the ir- 

 regular contraction of different parts of the 

 protoplasm. The filaments also emerge 

 from the tubes and break up ; and the frag- 

 ments then exhibit an oscillating movement 

 like that of a balance, together with an ad- 

 vance in a longitudinal direction. Lynybya 

 (PI. 8. fig. 10) does not appear to oscillate, 

 at all events when in long filaments ; Spini- 

 lina and other forms exhibit only a tremu- 

 lous oscillation ; Didymohelix probably ac- 

 2o 



