ON THE STRUCTURE OF OSCILLATORIiE. 251 



marked ; and through the middle of the filament runs a deep 

 green thread, somewhat tortuous like a swollen vein, perforat- 

 ing and connecting the cells from one end of the filament to 

 the other, forming its axis, and presenting an instance of a 

 contractile substance serving as an apparatus for locomotion 

 unexampled in the annals of vegetable physiology (figs. 14, 

 15). Their structure is, however, not so simple as one would 

 imagine from the description and drawings I have given ; 

 they present, on the contrary, so complicated and varying an 

 aspect, that it is next to impossible to give an adequate repre- 

 sentation of them. However, under a good object-glass 

 (l-8th), and at a certain focus, they appear as simple as 

 represented ; and I would add, it is only when seen tlius that 

 their extraordinary motions, which differ in some respects 

 from those of other Oscillatoricc, may be clearly observed. 



The motions of the Oscillatorice are indeed so singular that, 

 while some have in vain attempted to explain them as partly 

 external and altogether physical, others are not wanting who 

 have come to the conclusion that they must be animalculse, 

 solely on the strength of their apparent voluntary movements. 

 Dr. Hassall, for instance, on the former supposition, says : 

 " The filaments are very straight and elastic, and when they 

 are placed for observation on the field of the microscope, 

 they are bent out of their natural straight line, and make an 

 effort to recover it ; currents almost impei'ceptible in the liquid 

 in which they are immersed, and perhaps unequal attractions, 

 are causes amply sufhcient to explain their motions," The 

 most superficial examination, however, is sufficient to show 

 the futility of these arguments, and I would refer the reader 

 for a complete answer to them to a note of Captain Car- 

 michael, which will be found in Hooker's ' Flora ' under 

 Oscillatoria ; and I will only add that a drop of Tinctui'e of 

 Iodine, or an aqueous Tincture of Opium,* does neither 

 interfere with their efforts to recover their straight line, i. e., 

 with their elasticity, nor with the imperceptible currents of 

 the liquid in which they are immersed, but, nevertheless, 

 puts a stop to their motions. But, before referring further 

 to the cause of these motions, it will perhaps be desirable 

 to define strictly in what they consist. They are, generally, 

 not inaptly described as the oscillating of a balance with 

 an advance in a longitudinal direction ; but I must mention 

 that sometimes these motions are slow, at others quick and 

 effected by jerks, but the motion itself consists in the 

 revolving of the filaments ; they roll over and over, and 

 forward with a sudden start and then recoil, so that their 

 * ExiDOSurc to tlie vapours of chloroform produces the same effect. 



