Journal of Applied Microscopy. 



73 



with a little cotton on the bottom answer 

 very well. 



The antiseptic cotton which seems 

 best adapted to this purpose is prepared 

 by soaking ordinary cotton in a solution 

 of water 100, alcohol 20, and copper sul- 

 phate 3. The cotton should be dried 

 slowly, for if heated too much it chars 

 easily 



In a comparative experiment, about 

 fifty tubes of agar bouillon were treated 

 in this way, fifty left in the laboratory 

 without any protection but the ordinary 

 cotton plug, and fifty more with the ordi- 

 nary plug put in a closed jar. In three 

 months all of the first lot were in perfect 

 condition; the second lot had evapor- 

 ated to one-third of their original bulk, 

 and of the third lot only one tube 

 remained uncontaminated with mold. 



There is no danger that the antiseptic 

 will injure the culture medium for the 

 reason that any traces which may be left 

 on the upper part of the tube are com- 

 pletely wiped off in extracting the second 

 plug. 



Frederic T. Bioletti. 



University of California. 



On the Demonstration of Nuclear 

 Motion in the Circulating Proto- 

 plasm of a Cell. 



Chara Fragilis is selected. The plant 

 is widely distributed in fresh, pure, quiet 

 waters, it is described and figured in 

 Strasburger's " Das Botanische Practi- 

 cum" and in Bessey's botany. The stu- 

 dent must acquaint himself with the 

 bright red male reproductive organ, to 

 be found just below the leaf; if this is 

 crushed under the cover glass, the manu- 

 bria may be seen — club-shaped cells, 

 with brownish chromosomes but with a 

 considerable clear space at each end. 

 They may be known by the further fact 

 that to the top of each the whiplash-like 

 jointed appendages which contain the 

 spermatozoids are attached. These 

 manubria have a circuit of about five- 

 eighteenths of a millimeter. In May, 

 just before the ripening of the sperm- 

 atozoids, the protoplasmic contents, in- 

 cluding the nucleus of the cell, will be 

 fcund in rapid circulation. I have seen 

 the nucleus make twenty-six rounds of 

 the cell in a minute, that is, it moves at 

 the rate of 7.2 millimeters in a minute, or 

 more than four times as fast as the fast- 

 est rate given for the motion of proto- 

 plasm in a cell, in Goodale's Physiologi- 

 cal Botany. 



D. W. Dennis. 



Earlham College, Richmond, Ind. 



If pleased with the Journal, give us 

 your support — financially. 



A Preservative for Fresh Water 

 Sponge. 



I find the following solution to be of 

 value in preserving fresh water sponge: 

 Pure Glycerin §. 

 3% Formalin J. 



As every laboratory worker knows, 

 alcohol not only takes the color from 

 such specimens, but also from the back 

 upon which the sponge is growing, soon 

 becoming so discolored as to completely 

 hide the specimen. Spongalla viridis 

 was kept three months in the above 

 solution before it lost color; the back was 

 not attacked and the liquid has remained 

 permanently clear, showing the external 

 anatomy of the sponge in a beautiful 

 manner. It remains to be seen if a 

 weaker solution will not be even more 

 satisfactory. Its general usefulness in 

 preserving specimens for exhibition 

 without decolorizing them is too well 

 known to need comment here. 



F. L. Washburn, A. M. 



Department of Biol., Univ. of Oregon, 

 Eugene, Oregon. 



Two Photographic Dodges. 



I think it is Pringle, in his work on 

 photo-micrography, who says that cer- 

 tain preparations refuse to be well pho- 

 tographed. Just such a preparation 1 

 have in my collection, and it is an ex- 

 quisite transverse section of the human 

 spinal cord stained with gentian violet. 

 I tried Various plates, various exposures, 

 and various lenses, and very mucn 

 patience, but all to no purpose. I could 

 not get a clear, contrasty negative. I 

 varied the developer, but it was of no 

 use; the fine, delicate tracings of the 

 nerve-fibres in the structure would be 

 about as strong as the background of the 

 negatives. I had heard and read about 

 intensifying negatives — had tried it in 

 photo-micrography as an experiment, 

 and had given it up as rather a compli- 

 cated and bothersome work, and yet 

 this is the only remedy by which a good 

 and even an extra-good negative can be 

 obtained with objects of this class. I do 

 not think that the method I use is a new 

 one, but I claim it to be the simplest and 

 most expeditious. I have two four-ounce 

 bottles. No. 1, I nearly fill with water 

 and then add a small quantity of bi- 

 chloride of mercury (corrosive sublimate) 

 viz., as much as will dissolve in the 

 water. If crystals are used, one need 

 not be particular, as only a certain 

 quantity will dissolve, and the rest of the 

 crystals remain at the bottom of the bot- 

 tle and must not be pooired out when 

 using the solution. If the pulverized 



