Vol. LI August, 1926 No. 2 



BIOLOGICAL BULLETIN 



OBSERVATIONS ON MOTILITY IN CERTAIN 

 CYANOPHYCE^:. 1 



EDWARD S. CASTLE. 



The power of spontaneous movement in the blue-green algae 

 has been stated by many authors to be confined to the family 

 Oscillatoriaceae, occurring characteristically in the vegetative 

 filaments of Oscillatoria, Phormidium, Spiridina and Arlhrospira, 

 and occasionally in the hormogonia of related genera and even 

 of such Heterocysteae as Nostoc, Scytonema, and Rivularia. In 

 addition, DeBary (1863) and Phillips (1904) have described 

 motion in vegetative filaments of the genus Cylindrospermum, a 

 member of the Nostocaceae. 



Recently, however, two species of Anabcena occurring on the 

 estate of Mr. E. F. Atkins at Soledad, Cuba, and studied by the 

 writer in the Harvard Laboratory there, were found, although 

 belonging to the Nostocaceae, to show consistent motility like 

 that characteristic of the Oscillatoriaceae. These two species 

 were both commonly collected, forming thin scums on damp earth 

 in roadside ditches. In culture bottles they spread rapidly up 

 the sides of the glass in a manner resembling an active Oscillaloria, 

 finally covering the whole inside surface with filaments packed 

 side by side in a single layer. Although exhibiting an active 

 motility like that regarded as characteristic of members of the 

 Oscillatoriaceae, the filaments of both these species were torulose 

 and consistently contained heterocysts that conclusively excluded 

 them from that family. The larger of the two forms (Fig. ib) 

 regularly produced spores and in all essential characteristics 

 justified being identified as a species of Anabana; the other, 

 smaller form (Fig. id), although it never developed spores during 



1 Studies from the Biological Laboratory in Cuba (Atkins Foundation) of the 

 Harvard Institute for Tropical Biology and Medicine, No. i. 

 6 69 



