EECHEATIVE SCIENCE. 



155 



nearly at our own door, we find on tlie 

 gravelled path., at tlie base of tlie wall, a 

 lively crisp-looking little vegetable, some of 

 which, is secured, and we have material 

 enougb for some hours' careful examination, 

 and, if time permitted, montbs,' it may be 

 years, of study. 



Let us take out the microscope ; some 

 slides and thin glass-covers, and a tumbler 

 of clean pure water, will be wanted ; and it 

 may be as well to have a little bottle of 

 glycerine, and another of asphalte varnish, 

 for the preservation of tbe subjects of ex- 

 amination. The magnifying power required 

 will be tolerably high, say about two hundred 

 diameters. We will take a little of the ma- 

 terial obtained from the pool, black from the 

 close crowding of the little threads composing 

 it, remove it with the point of a penknife to 

 a slide, and then put on a cover. In the 

 meantime, the portion from which it was 

 taken may be put into a watch-glass, or other 

 shallow vessel, with a little water. Eaise the 

 tube of the microscope, lest the object-glass 

 be injured by touching the slide or the wate • 



Fig. 1. — Oscillatoria. a, portion of a mass under a 

 moderate magnifying power ; b, end of one filament, 

 with cilia (?) much more highly magnified; c, fila- 

 ment breaking upj d, sporange (?). 



upon it, and carefully lowering it till rightly 

 focussed, look what we have got. "Why the 

 whole field is in motion! it looks as if we 

 had a number of little slender worms, of a 

 pale copperas, or verdigris-green colour, uni- 

 form in diameter, and with a sufficient power 



and good light, bars or stripes at short 

 intervals may be seen passing across them. 

 Here are some that look as if they might 

 be fastened together like a bundle of fag- 

 gots, with those on the outside writhing and 

 twisting as if they would free themselves 

 from an unwelcome embrace. Some have 

 succeeded in the attempt, and are passing 

 across the field with an undulatory motion ; 

 others are imitating the action of a pendu- 

 lum, whilst here is one turning what might 

 be taken for a head, with which it would see 

 what is going forward behind it. The 

 peculiar character of these movements has 

 caused the name of Oscillatoriae to be given 

 to the tribe (Fig. 1). 



How do they moveP is the first question 

 that suggests itself, and it is not easily to be 

 answered; for upwards of a century has it 

 been debated, and it is yet hung round with 

 doubts. It has been suggested by Dr. Harvey, 

 that the appearance of wave-like flexure and 

 oscillation may be due to onward progress 

 in a spiral direction. This view is enter- 

 tained by Dr. F. D'Alquen, in a very able 

 article in the " Quarterly Journal of Micro- 

 scopical Science" (vol. iv. p. 245), where the 

 whole subject is treated at length, and a 

 source of motive power described in one 

 species, which, if the author be correct, would 

 be, so far as known, new and unique in the 

 vegetable kingdom, an irritable contractile 

 fibre passing down the centre of each fila- 

 ment. Our own observations lead us to 

 think that the motion is really in a spiral 

 direction, but to what it may be due we do 

 not venture to give a decided opinion. One 

 observation we made, however, seems very 

 much to the point : on doubling oiir magni- 

 fying power in this instance, as represented 

 at b (Fig. 1), a number of fine threads were 

 seen projecting all round the end of the fila- 

 ment, to one of which a minute particle of 

 dirt adhered ; we could thus see that the fila- 

 ment was turning rapidly round, and found 

 it difficult to resist the belief that the lash- 



