1880.] 



MICROSCOPICAL JOURNAL. 



159 



Smith's exquisite slides. To illustrate 

 this, I will say that within a few days I 

 received from Prof. Smith, among other 

 slides, one of Gomphonema Brebissonii 

 upon which could be found, in addition to 

 the typical form, G. actaninatitin in vari- 

 eties that shaded off into very fair repre- 

 sentives of G. capitatutn. 



In the same lot of slides were sHdes of 

 Gomphonema herculaninm, and Cyclo- 

 tella Oregonica ; and in each of these two 

 slides could be found valves of Gomphon- 

 ema which were probably the same as 

 some of the intermediate varieties of 

 acuminatum in the first, yet none of them, 

 looked at alone, would be called acum- 

 I'natutn. C. M. VORCE. 



NOTES. 



— It has long been known that the visi- 

 bility of fine markings on diatom-frustules 

 was dependent upon the refractive indices 

 of the mounting medium and of the 

 material of which the diatom is composed, 

 the greater the difference the more visible 

 the markings become. Mr. J. W. Stephen- 

 son has given a table indicating the relative 

 visibility of silica in various media, which 

 we reproduce as follows : 



Ref. index. Visibility. 



Water, .... 1.33 10 



Balsam 1.54 11 



Bisulphide of Carbon, 1.68 25 

 Solution of Sulphur in 



bisulphide of carbon 1.75 32 

 Solution of Phosphor- 

 us in ditto. . . . 2.10 67 

 We take the above table from Science. 



— Our thanks are due to Dr. R. H. Ward 

 for a neat pamphlet containing his address 

 delivered at the meeting of the American 

 Society of Microscopists at Buffalo, last 

 year. We have already published the 

 greater part of his address. 



— The prevalent idea that Hydra swal- 

 lows by taking its prey in its tentacles and 

 turning tentacles and all into its stomach, 

 has been contradicted by Mr. Hartog in 

 the Quarterly Journal of Microscopical 

 Science. It is quite time that such an er- 

 ror should be corrected, and it is strange 

 that it could be so long entertained, for if 

 any observer will place a Hydra in a live- 

 box with a Cyclops or other small entom- 

 ostracan, he will be able to watch the 

 process of capturing and swallowing the 



animal in a few moments, and it is quite 

 an interesting operation to observe. 



— A German writer claims to hav6 de- 

 tected a thread-like, reticulated structure 

 running through the protoplasm, nuclei 

 and chlorophyll granules of growing cells. 

 He also states that the threads pass from 

 cell to cell, through orifices in the cell-walls. 

 A power of 900 diameters is necessary for 

 these investigations, which were made on 

 the epidermal and parenchymatous cells of 

 Draccena and of Rhododendron ponticum. 



— It would seem, from the results of 

 some experiments by Prof. Schmitz, of 

 Bonn, that all cells of Thallophytes con- 

 tain one or more nuclei. In no instance 

 has he found a growing cell without a 

 nucleus. The reagent employed for de- 

 tecting the nuclei was an aqueous solution 

 of hasrmatoxylin. 



— Not long ago we received from Mr. 

 C. L. Peticolas, of Richmond, a number 

 of slides of diatoms such as he prepares 

 for sale. We have examined some of 

 them with great care, and we are pleased 

 to express our admiration of the beauty 

 of many of the forms, and for the general 

 excellence of the cleaning and mounting. 

 No cabinet can be quite satisfactory with- 

 out some of Mr. Peticolas' sfides, for we 

 are disposed to regard them as the best 

 lot of diatom-slides of their kind that can 

 be found in the market. 



— An aquarium cement, said to be used 

 at the London Zoological Gardens, suitable 

 for either salt or fresh-water, is made as 

 follows : 



Litharge, fine, white, dry sand, plaster 

 of Paris, of each 1 gill ; finely pulverized 

 resin, ]A^ gill. Mix, and make into a paste 

 with boiled oil containing a dryer. Beat 

 well and then allow it to stand four or five 

 hours, but not longer, before using. 



MICROSCOPICAL SOCIETIES 



CENTRAL NEW YORK. 



A regular meeting of this Society was 

 held on the evening of Tuesday, June 

 29th, at the office of Dr. Aberdein, in 

 Syracuse, President Collins in the chair. 



Dr. Aberdein read a paper giving a 

 general statement of the usual method of 

 mounting objects, for the benefit of those 

 members of the Club who had had little 



