Journal of Applied Microscopy. 



In practice about five times as much 

 liquid is taken as muscle, and the piece 

 of muscle should not be larger than one's 

 little finger. A^ery simall pieces should 

 be worked on within a few hours, two to 

 five, while larger pieces may wait longer. 

 That is there is too great hardening of 

 the tissue if the solution acts on a small 

 mass for a considerable time. For a 

 simple, temporary demonstr'ation a shred 

 or fascicle is removed from the mass of 

 muscle and teased out in water or in 

 some of the dissociating liquid, but if 

 one wishes to de'monstraite the finest de- 

 tails, and to see with clearness the vari- 

 ous discs described in modern works he 

 should proceed as follows: A small 

 fascicle is teased very thoroughly in a 

 driop o'f water. One miay use a tripod 

 magnifier to make sure that the teasing 

 is thorough. The water is drained off and 

 two or three drops of a two per cent, 

 solution of erythrosin in fifty per cent, 

 alcohol is added and left for five minutes; 

 or one may use a two per cent, aqueou.? 

 solution of eosin. Either of these agents 

 will stain the parts of the fibrils which 

 appear dark in unstained preparations, 

 but the erythrosin is preferable. After 

 five minutes the stain is poured off care- 

 fully, and the fibers are washed with 

 several drops of water and then dehy- 

 drated with 95 per cent, or stronger, al- 

 cohol (two or three pipettes full will suf- 

 fice). A drop of clearer (carbol-turpen- 

 tine or carbol-xylene) is added after 

 pouring off the alcohol, and the fibers 

 are carefully separated with needles, and 

 after pouring off the clearer a cover 

 spread with balsam is put over them. If 

 the preparation is successful, and most 

 of them are, one gets a very satisfactory 

 view of the minute structure as well as 

 of the general structure, as some of the 

 fibers will show with perfection the 

 transverse striae, others the longtitudi- 

 nal striae and the isolated fibrils. For 

 seeing the minute details, a good hom'o- 

 geneous immersion objective and careful 

 lighting are necessary. 



If a muscle is found to give go'od pre- 

 parations it may be preserved for at 

 least three years in fifty per cent, alco- 

 hol and give good results. 



One feature of our February issue will 

 be the first of a series of illustrated ar- 

 ticles entitled "Representative American 

 Laboratories. " The laboratories of Cor- 

 nell University will be the first subject. 



A Table of Ocular Micrometer 

 Values. 



I have been accustomed for several 

 years to make use of a table of ocular 

 micrometer values in all my microscopic 

 measurements and to recommend to stu- 

 dents the desirability of preparing such 

 tables for their own use. At the risk of 

 calling attention to what may already 

 be widely employed, though I do not re- 

 member to have seen any allusion to a 

 table of this kind, I will give an exact 

 copy of one of the tables which I make 

 use of and a brief statement concern- 

 ing it. 



only a limited time— two to twenty-four 

 hours. See " Proceedings of the Amer. 

 Micr. Soc. for 1897.") It was in this series 

 of experiments, made three years ago, that 

 the special excellence of platinum chlorid 

 for demonstrating the longtitudinal strla- 

 tion and fibrils of muscle was discovered. 



The essential feature of this table is, 

 that it gives in a compact form the 

 value not only of one division of the ocu- 

 lar micromeier, but the values corres- 

 ponding to each of the nine digits, from 

 which one can quickly compute mental- 

 ly the value of any number of divisions. 

 If the real image of an object measures 

 ten divisions of the micrometer or less, 

 the size of the object may be read direct- 

 ly from the table, provided that the im- 

 age corresponds with an exact number 

 of the divisions. If, on the contrary, the 

 size of the image exceeds a certain num- 

 ber of divisions by some fraction of a 

 division, the value of this fraction, esti- 

 mated in tenths of a division, may be 

 quickly ascertained (a tenth of the cor- 

 responding unit value in the table) and 

 mentally added to the value of the whole 

 number of divisions. For example, a 

 given object viewed with objective A 

 measures 7 divisions (89.6 ;t^) and the frac- 

 tion, estimated at 0.5 of a division, (6.4 ju); 

 the sum of the corresponding values is 

 seen at a glance to be 96//. Likewise, if 

 the object measures more than 10 divi- 

 sions, its value is quickly found from the 

 table by a simple multiplication or addi- 

 tion. For example, 18 divisions have the 

 value of 3x6, or 10 plue 8, divisions; 

 17 divisions are equivalent to 10 plus 7, 

 or, better, 8 plus 9 divisions, since the 

 value of 8 and 9 are contiguous in the 



