1883] 



MICROSCOPICAL JOURNAL. 



59 



lake, but not in the shallows where they 

 would be exposed to actual freezing. 



The springy pools referred to are 

 rarely, or never, frozen over. Spirogv)-a 

 I procure in the same way, for winter 

 study. Of course, it is not in fruit. 



William R. Dudley. 



IMOTION OF DiATOM.S. 



To THE Editor. — Inasmuch as all 

 efforts to find some outside means of 

 movement have failed, is it not very prob- 

 able if not almost certain that their move- 

 ments are produced within the frustule .'' 

 The front view of naviculas, and of all 

 elongated forms having a central nodule, 

 usuklly show a division of the vegetable 

 contents into two or four parts, having a 

 main central alley between them running 

 both lengthwise and crosswise. Cur- 

 rents seem to be produced by some 

 means, through these central alleys, and 

 water is forced out of the porous frustule 

 at the ends or sides as through a sieve, 

 inasmuch as the cross lines of diatoms 

 are merely attached globules of silex with 

 spaces between. These globules of si- 

 lex, being so close together, prevent a 

 clear vision of the interior part of the 

 frustule but it seems probable that vibra- 

 tile cilia line the surface of the vegetable 

 matter within, and these beating in uni- 

 son cause the water to flow in one direc- 

 tion or another as they more or less unite 

 in their action. Could a fresh frustule be 

 broken open, I believe the surface of the 

 vegetable matter within would show this 

 presumed ciliated arrangement. 



J. M. Adams. 



[Our correspondent, like many others, 

 finding no satisfactory solution of this 

 problem through observation, resorts to 

 speculation concerning it. We must cau- 

 tion the reader that it is not yet known 

 whether the frustules are perforated or 

 not, as will be seen from an article soon 

 to be published in these columns. As 

 for the presence of cilia within the 

 diatoms, we have no more reason to ex- 

 pect to find cilia there than in any other 

 cells in which the movement of proto- 

 plasm has been observed — as in dismids, 

 or in the cells of higher water-plants, for 

 example. Moreover, diatoms are not the 

 only plants which move without visible 

 cause. The dismids, for instance, move 

 with vigor, and they are not enclosed in 

 a silicious shell which obstructs examina- 

 tion of the interior. In young dismids 

 especially, the cyclosis can be examined 

 with satisfaction by high-powers. Look- 



ing over the algae, we find that the 

 oscillaria are quite as remarkable in 

 their movement as the diatoms, and 

 we cannot yet explain it, and in 

 the animal kingdom the jregarina? also 

 move without giving the least indica- 

 tion of how the motion is produced. It 

 is a subject for still further investigation, 

 and we have no doubt that with good ob- 

 jectives, supplemented by staining fluids 

 properly applied, the cause of the move- 

 ments will soon be discovered. — Ed. 



MICROSCOPICAL SOCIETIES. 



At the meeting of the New York So- 

 ciety held February i6th, Mr. C. Van 

 Brunt spoke on the subject " Desmidia- 

 ceaf." 



The most common forms of desmids, 

 he said, belong to the genera Clostei-iiiin 

 and CosniariujH. The desmids differ 

 from diatoms in the absence of silex 

 from their cell-walls, and the endochrome 

 of diatoms is distinguished by its color 

 and the presence of iron. In the desmids 

 a constant circulation of granules can be 

 observed just within the cell-wall at the 

 sides and at the ends. The desmids 

 have a power of movement, which is still 

 unexplained. They cannot be preserved 

 by mounting them in any way yet tried 

 by the speaker. They keep for some 

 time, but after a few years the barest out- 

 line of their form remains, and finally 

 even this disappears. The principal 

 methods of multiplication of desmids, — 

 by simple division and by the formation 

 of sporangia — were briefly described. 



In the discussion which followed, Mr. 

 Van Brunt stated that since he had ob- 

 tained very fine lenses he had endeavored 

 to discover the cause of movement, but 

 had failed to do so. The movement is 

 slow, then there is a sudden jerk. He 

 had found great difliculty in drawing des- 

 mids with a camera lucida, for they change 

 their place before it is possible to trace 

 the entire outline. 



Mr. J. D. Hyatt read an interesting let- 

 ter from Rev. Samuel Lockwood, con- 

 cerning some shells in a marl bed in 

 New Jersey bored by a sponge, and 

 showed some specimens illustrative of 

 the subject. 



Mr. W. H. Mead exhibited and de- 

 scribed a Nachet travelling microscope, 

 which was provided with one of the 



