440 Journal of Applied Microscopy. 



thread appears as a delicate red ribbon bordered by blue granules, the staining 

 may be regarded as a success. If mitotic figures have been stained with cyanin 

 and erythrosin, a first-class preparation should show blue chromosomes and red 

 spindles ; if stained with safranin and gentian-violet, the chromosomes should be 

 red and the spindles violet. 



In staining growing points, apical cells, young embryos, antheridia, archegonia, 

 and many such things, the cell walls are the principal things to be differentiated 

 if the preparations are for morphological study. As a rule it is better in such 

 cases not to use double staining, but to select a stain which stains the cell walls 

 deeply without obscuring them by staining starch, chlorophyll, and other cell 

 contents. For example, try the growing point of Equisetum. The protoplasm 

 of such growing points is very dense. If Delafield's ha^matoxylin and erythrosin 

 be used, the hsematoxylin will stain the walls and nuclei, and will slightly affect 

 the other cell contents, but the erythrosin will give the cytoplasm such a dense 

 stain that the cell walls will be seriously obscured. It would be better to use 

 haematoxylin alone. The same suggestion may well be observed in tracing the 

 development of antheridia, archegonia, embryos, and similar structures. 



Permanent preparations are an absolute necessity for the greater part of most 

 advanced work, but let us not imagine that we cannot examine anything until we 

 have made a permanent mount. It would be impossible to make a permanent 

 mount of the rotation of protoplasm. It is better for many purposes to look at 

 motile spores while they are moving. Use Spirogyra while it is fresh and green 

 (if you can), and use permanent preparations only to bring out nuclei and other 

 details, which are not so easily seen in living material. Examples might be 

 multiplied. 



( To he Contimied.) 



The Demonstration of Alcohol and CO2 in Yeast Cultures. 



In laboratory work on yeast, the formation of alcohol as a result of the gro^vth 

 of the plant in a sugar solution should be demonstrated. The method usually 

 employed — that of distilling off the liquid and demonstrating its character by 

 taste, odor, inflammability, etc., is too troublesome for the average student, and I 

 have found the iodoform test for akohol much more satisfactory. If a few drops 

 of iodine solution be added to the tube in which the yeast is growing, and then 

 enough KOH solution to destroy the color of the iodine, iodoform will be 

 produced, and can be recognized by its characteristic odor. It is best to perform 

 the experiment first with a little dilute alcohol, and then compare with this 

 result that obtained after treating the sugar solution as above. The CO 2 given 

 off by the liquid in which yeast is growing can be demonstrated most easily by 

 suspending a drop of lime water in the test tube on the end of a glass rod. 

 The cloudiness set up in the lime water can be demonstrated much more easily, 

 and just as satisfactorily in this way, as by the more complicated devices usually 

 employed. A. L. Treadwell. 



Miami University. 



