220 OSCILLATORIACE^. 



versely striate, until just before the breaking up of the plant. 

 But in some LijnghijcB, the endochrome exists, from an early 

 period of growth, in the form of separate lenticels. Such plants 

 have a structure very similar to that of the simpler Batujice, 

 through which genus a connection is established with Ulvaceoe, 

 or of Hormospora, the conterminous genus on the side of the 

 Palmellaceae. With the Nostochaceae there is a close affinity 

 established through Sphajrozyga and Spermosira ; the latter 

 of which, when very young, has a strong resemblance to an 

 Oscillatoria. 



Many plants of this order are celebrated for their semi- 

 aniraality (according to the views of some naturalists) ; at 

 least, for having independant motions, the cause of which is 

 unexplained. The OscilUilorioi, Spirulina, and others have 

 this locomotive power in a greater or less degree. It has a 

 threefold character. First there is a movement of the fila- 

 ment from side to side ; one end being kept pretty steady, so 

 as to form a central pivot, while the other end oscillates, like 

 a pendulum, describing segments of circles in its passage. 

 This sort of motion, which gives name to the genus Oscilla- 

 toria, though often languid, or not to be observed when spe- 

 cimens are examined, is sometimes exceedingly vivid, the 

 threads rapidly changing place from one side of the field of 

 view to the other. Coincident with this oscillation, we often 

 observe the end of the filament which describes the circle to 

 hend first to one side and then to the other, something as the 

 head of a caterpillar or a worm does when the animal is 

 gliding over unknown ground, or as if the creature were 

 seeking something at either side of its line of march. This 

 sort of movement is less frequently noticed than the oscilla- 

 tion, but I have repeatedly witnessed it, and it far more 

 nearly resembles the movement of an animal than any other 

 vegetable motion with which I am acquainted, except, per- 

 haps, that oi' Bacillifria parado.va. The third sort of motion 

 is more the result of the other two than an independent 

 movement: it is a simple progression. The whole phe- 

 nomenon may perhaps be resolved into a spiral onward 

 movement of the filament. If a piece of the stratum of 

 an Oscillatoria be placed in a vessel of water, and allowed 

 to remain there for some hours, its edge will first be- 

 come fringed with filaments, radiating as from a central 

 point, with their tijis outwards. These filaments, by their 

 constant oscillatory movements, are continually loosened 

 from their hold on the stratum, cast into the water, and at 



