'^ 7 * 2 ALCkffi CONFERVOIDE^:. [OsciUatoria. 



spection I could make, the filaments in the two following spe- 

 cies are cylindrical and not articulated but merely contracted 

 at certain equal distances into a series of imperfect or pervious 

 cells, each including- a couple of sporidia. These contractions 

 form the only essential difference between this genus and 

 Lyngbya." Carm. MSS. 



1. R. le?itigera, Carm. {short-jointed Rosaria); locules strongly 

 contracted, as long' as broad, sporidia lenticular. 



On various small Algce. Appin, rare, Captain Carmichael. — " Filaments 

 gregarious, 1 — 2 lines in length, curved, of an olive colour, regularly 

 contracted at equal distances to one-fourth of the diameter of the tube; 

 celteas long as broad, containing two fentiform sporidia. At first, the 

 sporidia are in one mass, marked only by a transverse stria." Carm. 

 MSS. 



2. R. globifera, Carm. (long-jointed Rosaria); locules subcon- 

 tracted twice as long as broad, sporidia globular. 



On Utva ? percursa ; extremely rare. Appin, Capt. Carmichael. — 



"Filaments scattered, 1 — 2 lines in length, of a fulvous colour, not above 



half the diameter of the preceding species. Cells slightly contracted, 



twice as long as broad, containing two globular sporidia." Carm. MSS. 



76. OseiLLAToitiA.i Vaach. OsciUatoria. 



Filaments invested by a common mucous matrix, rigid, elas- 



] Captain Carmichael has the following ingenious remarks under OsciUatoria, 

 in his unpublished "Alc/ce Appinenses." " I have been induced to bestow con- 

 siderable attention on such of the species as fell under my notice, on account of 

 the singular motion remarked in the filaments by various Naturalists ; and I 

 do confess, that the result is something like conviction that they belong rather 

 to the animal than to the vegetable kingdom. This motion or oscillation has 

 been attributed to various causes; to the rapidity of growth, to the action of 

 the light, or to the agitation of the water in which the specimens were im- 

 mersed for inspection; but none of these affords a satisfactory explanation : 

 the last may be put to the proof by a very simple contrivance. Let a small 

 portion of the stratum be placed in a watch-glass nearly filled with water, and 

 covered with a circular film of talc, so that its edge may touch the glass ; the 

 water will be rendered as fixed as if it was a piece of ice. The glass may now 

 be placed under the microscope, and the oscillation of the filaments viewed 

 without any risk of disturbance from the agitation of the water ; by following 

 this course, it will be speedily perceived that the motion in question is entirely 

 independent of that cause. 



" The action of light, as a cause of motion, cannot be directly disproved, be- 

 cause we cannot view our specimens in the dark; but indirectly there is no- 

 thing easier. If a watch-glass, charged as above, be laid aside for a night, it 

 will be found that by next morning, not only a considerable radiation has 

 taken place, but that multitudes of the filaments have entirely escaped from the 

 stratum; both indicating motion independent of light. Rapidity of growth 

 will show itself in a prolongation of the filaments, but will not account for this 

 oscillation to the right and left : and still less for their travelling in the course 

 of a few hours to the distance often times their own length from the stratum. 

 This last is a kind of motion, unexampled, I believe, in the vegetable kingdom. 

 There is another point in the natural history of the OsciUatoria., which favours 

 the opinion that they are animalculse. It is the extremely limited term of their 

 existence. The community, if I may so call it, lives for several months; but 

 the individuals die off", and are succeeded by others with a rapidity to which 

 there is no parallel among genuine plants. If a small portion of stratum, say 

 one-fourth of an inch in diameter, be left for 3 or 4 days in a watch-glass, filled 

 with water, the whole area of the glass will be found covered with a thin 

 transparent pellicle or incipient stratum, derived from the filaments that had 

 successively radiated and died in the course of that short period." 



