236 



THE AMERICAN MONTHLY 



[December, 



Jotirnal^ p. 175, the creatures being 

 not the Nautilus, as he at first sup- 

 posed, but probably a species of 

 Velella . 



NOTES. 



— Mr. Debes recommends the cultiva- 

 tion of diatoms for biological purposes. 

 The collections should be placed in a cool, 

 airy place, shielded from the sun, and 

 only provided with a very small supply 

 of water. It is better to keep them only 

 thoroughly moistened, for with more 

 water, unless it be constantly changed, 

 fungi are likely to grow and the culture 

 becomes turbid and foul. Cultures may 

 be continued for months and years, suc- 

 cess depending largely upon the proper 

 regulation of the supply of water. It 

 has been observed that in most cultures 

 the species change, new forms at first 

 only found singly, replace the originally 

 most abundant species, but after a while 

 these disappear and are in turn replaced 

 by their predecessors. — H. 



— Mr. E. W. Holway has sent us a 

 well-made photograph of a spider's foot. 

 Such exceedingly yellow specimens as 

 the spider's foot usually is, are difficult 

 subjects to photograph, requiring long ex- 

 posure and restrained development to 

 bring out the detail. The one before us 

 was taken with a % objective, A ocular 

 and achromatic condenser used with a 

 bull's-eye and blue and ground-glass 

 shades, and received an exposure of 18 

 seconds. Mr. Holway states that he has 

 had some difficulty in photographing fun- 

 gus spores — -some of them photograph 

 well, while others do not. We do not 

 know why there should be any such dis- 

 crepancy of results. Perhaps some reader 

 can explain it. — H. 



— We believe it will be doing a service 

 to pharmacy to call attention to the fact 

 that a really efficient compound micro- 

 scope may now be had at a cost consid- 

 erably less than it has been possible to 

 obtain one heretofore. The Chicago Col- 

 lege of Pharmacy has recently imported 

 twenty additional instruments from E. 

 Leitz, Wetzlar, Saxony, which we have 

 carefully examined. "They are really effi- 

 cient, honestly made instruments, capa- 

 ble, we believe, of answering all the ordi- 

 nary needs of the pharmacist, and the 

 price for which they may be had at retail, 

 JJ525, seems to us as low as is possible to 



produce a really good instrument. The 

 stand is, of course, very simple, but firm 

 and well made. It has a plain brass stage 

 with spring clips, a straight or unjointed 

 back, a horse-shoe base, a good fine ad- 

 justment, a concave mirror, adjustable in 

 two planes, one eye-piece and two objec- 

 tives, one of the latter about equivalent to 

 a two-thirds, and the other to a one-fifth, 

 giving a range of magnifying powers of 

 from about 50 to about 400 diameters. The 

 objectives are of better quality than those 

 ordinarily sold in the student series, the 

 higher power easily resolving Plein'osigjna 

 angulatmn by central light. The instru- 

 ments are not now for sale in this city, or, 

 so far as we know, in this country, but 

 some of our enterprising opticians will 

 probably soon keep them in stock. — West- 

 ern Druggist. 



— Speculations of physicists upon the 

 size of atoms and molecules are now 

 founded upon experimental data, and it is 

 probable that the size of the ultimate 

 atoms of matter is known to a very close 

 approximation, and even their weight has 

 been calculated. Not long ago we gave 

 some results of calculations of this kind. 

 Sir W. Thomson has found that the mean 

 distance between the centres of contigu- 

 ous molecules is between the ^V ^rid the 

 ^Jjj of a millionth of a millimetre. Prof. 

 G. J. Stoney has calculated the weight of a 

 molecule of hydrogen to be a twenty- 

 fifth grammet. Grammets are decimal 

 divisions of a gramme, of which the first 

 is a decigramme, the second a centi- 

 gramme, etc. 



— Mr. Walter Gardiner, who has been 

 engaged in the study of the continuity of 

 protoplasm in plant-cells for a number of 

 years, has found valuable assistance in 

 these investigations in the use of staining 

 agents. The so-called ' intercellular pro- 

 toplasm ' of authors consists of mucilage, 

 and is not protoplasm at all, although it 

 stains like the latter with the usual agents. 

 But he was able to distinguish the two 

 sulDStances by the use of methylene blue, 

 which stains cell-walls and mucilage but 

 does not stain protoplasm, and Hofmann's 

 blue, which stains protoplasm and cell- 

 wall but not mucilage. 



— As an example of patient watching 

 with the microscope we are much pleased 

 to cite the recent researches of a lady. 

 Miss Pereyaslavsteff, who is the director 

 of the Sebastopol Zoological Station. She 

 has succeeded in tracing the course of the 

 development of several species of rotifers 

 from the &gg to the adult form by watch- 



