ON THE STRUCTURE OF OSCILLATORI^E. 249 



brilliant ; in other instances the cells assume more of a 

 globular shape, and in this case, the filament, which is usually 

 straight, deviates to the right or left after each globular ex- 

 pansion, and from both sides tapers down into it. I believe 

 the latter form is but a more mature state of the former ; and 

 ultimately, at these joints, the filaments separate, setting the 

 globular cells free, which may, perhaps, justly be regarded as 

 (}0}iidia. In other filaments the striae are formed ; as it 

 seems, by a number of granules, though I believe they are in 

 reality to be found on each side of the cross-markings. As 

 these granules are only observable in some of the filaments, 

 and in others of the same species not, I think they denote a 

 peculiar stage of development, and I am strongly impressed 

 with the notion that these bodies are in some way connected 

 with reproduction. 



The growth of the Oscillatorics has been stated by some to 

 be so rapid that they grow 10-12 times their length in as many 

 hours, and otlicrs have gone so far as to attribute their motions 

 to the rapidity of their growth. Wy observations have 

 taught me to regard these notions as entirely unfounded and 

 fanciful. Even Kiitzing seems to share these extravagant 

 notions regarding their growth. He says (' Phycologia Germ. 

 p. 157, note) : " All the Oscillatorice grow so fast that their 

 growth may be watched and followed up while under observ- 

 ation with the microscope ; this fact explains the pheno- 

 menon, that when they are slowly dried on paper in masses, 

 the filaments are prolonged in all directions, forming a ray 

 around the mass." With all due regard for this distinguished 

 algologist, I think the fact cited admits of another, and what 

 seems to me the true explanation; the filaments, namely, 

 creep out from the mass, if I may apply this term to their 

 motions, wherever the presence of water facilitates their 

 movements ; in drying a mass of them on paper, the water 

 will naturally collect for some time at its circumference, and 

 allow the filaments to riggle out, forming thus the ray men- 

 tioned by Kiitzing. The formation of this ray is, therefore, 

 due to their protrusion, and not to a. prolongation of the filaments 

 themselves, which alone is implied when speaking of their 

 growth. I have frequently observed, if a small portion of 

 the flaky stratum of Oscillatoria, of a deep, glossy greenish- 

 black colour, as found under damp walls, covering the damp 

 ground to the extent of several feet, be placed in a watch- 

 glass with water, in a short time nearly the whole extent of 

 tlie glass will be found covered with single filaments, forming 

 a kind of pellicle, and at first sight this might be taken for an 

 instance of their remarkable growth ; but on examination, the 



