672 PE0CEEDING9 OF TUE SOCIETY. 



foreign matter. Ilic past January has been unusually stormy, nntl 

 the water consequently roll}', wliilo the filaments are not as well 

 developed as in some former years. 



" Five of the slides arc mounted dry, as tlie filaments, with rare 

 exceptions, cannot be seen in water. Slide No. G contains a drop of 

 water with the diatoms, as caught from a small stream from the faucet 

 in a muslin bag. The extreme temiity and hyaline character of the 

 filaments are the greatest hindrance to a more perfect examination of 

 them. They are seen to best advantage with a strong light and dark 

 background illumination ; sunliglit adding much to the etfeetiveness 

 of the observation. In slide No. 1, using 2/3 in. or 3/4 in. objective, 

 may be seen how regularly the filaments arrange themselves on the 

 slide ; frequently those of one diatom crossing those of another, all 

 maintaining a radial position with some degree of preciseness. This 

 fact alone would indicate a substance very difiereut in character from 

 the mycelium threails of an ordinary fungus. 



" When the diatom is examined edgewise, that is, in front view, 

 the filaments can be seen to proceed from near the lino of suture, but 

 whether from the internal contents of the frustule or from the ring 

 of the diatom I am unable to determine. If from the ring, I have 

 thought they might be siliceous, although recent experiments show 

 that they are consumed by the heat of an alcohol lamp, A drop of 

 water containing a few of these diatoms placed on a slide and allowed 

 to evaporate under the Microscope is interesting, and displays a phe- 

 nomenon not shown by any other diatoms that I am aware of. As 

 the line of evaporation proceeds on tlie slide, the diatoms frequently 

 disappear instantly ; in some cases leaving the filaments attached to 

 the glass, while in other cases, where there is but little foreign matter 

 to interfere, they may be found beyond the extent of the drojj, with 

 the filaments spread out as radially as if j^laced so artificially. If 

 the diatoms stand long enough for the water to become sour, the 

 filaments fall ofi*, and may be seen scattered about the slide, as in 

 No. 2. In some of the slides may be seen a few small discoids 

 without spines, which, when alive in the water, seem to possess 

 power to repel every light body from contact with them, so that a 

 distinct transparent anuulus as wide as the diameter of the diatom is 

 presented, A little blueing jilaced in the water imder the cover-glass 

 makes this more noticeable (see Amer. Mon. Micr. Journ., ii. (1882) 

 p. 8). This year I have noticed for the first time that these small 

 diatoms when dry have several small projections which, if in motion, 

 would seem to be sufficient to form the annulus. In some cases the 

 long filaments of S. NiagarcB have the appearance of being branched. 

 My opinion is that it is merely an overlapping," 



Mr. Bennett said that having examined Mr, Mills's slides, he 

 thought there was hardly sufficient evidence that the filaments were 

 part of the diatom ; they had more the appearance of epiphytic growths. 



Mr. Badcock said Mr. Mills's specimens v/ere different from those 

 which he had exhibited on a former occasion as occurring upon Suri- 

 rclla hifrons at Keston. These appeared to him to have a distinctly 

 pseudopodal character, having movements very much like an amoeboid 

 elongation and contraction, whereas these now shown very much 



