64 



Journal of Applied Microscopy. 



watch glasses. In this condition they 

 may be conveniently left over night, or 

 at least for a space of several hours. 



The next step is to take the watch 

 glasses and subject them to just suffi- 

 cient heat to melt the paraffln-xylol mix- 

 ture. I have found the sun's rays amply 

 sufficient, and besides very convenient. 

 After being thus heated for at least 

 three hours or until nearly all of the 

 xylol is driven off, the preparations are 

 ready for the paraffin bath. 



A rectangular tin box with some such 

 dimensions as six inches long by four 

 inches wide and one and one-quarter 

 inches deep, provided with a sheet of 

 glass as a cover, forms an excellent bath. 

 This is supported upon a copper triangle 

 eighteen inches long and six inches wide 

 at the wider end. The heat, either gas 

 or alcohol lamp, is applied at the pointed 

 end, and is regulated either by moving 

 the lamp or by moving the pan nearer 

 or further from the heated point (flg. B). 

 It is important to keep the paraffin about 

 two-thirds melted, as, if the entire 

 amount of paraffin in the pan becomes 

 melted, there is a possibility of too great 

 a temperature in the pan. 



^ 



Upon the top of the melted paraffin 

 are placed small rectangular paper 

 boxes (fig. C). These are readily made 

 by folding a piece of paper one and one- 

 half inches by two inches on the lines 

 indicated in the subjoined diagram (fig. 

 D). This is filled with melted paraffin 

 and into it the preparations are placed. 

 After imbedding for from four to six 

 hours, the objects are arranged properly 

 in the box and the box and par- 

 affin are lifted with forceps and 

 placed upon a basin of cold water. 

 In a few minutes the paraffin is 

 hardened and the paper may be 

 removed. Success with even the most 



delicate objects may be obtained if the 

 material is properly handled. Common 

 causes of failure may be enumerated as 

 follows: 



(1) Too sudden transfers are made 

 from one medium to another, therefore 

 use a number of different grades of 

 alcohol and many different proportions 

 of alcohol and xylol. 



(2) The transfer from the xylol to 

 paraffin is often too sudden. To remedy 

 this, allow plenty of time, and heat the 

 xylol-paraffin mixture very gradually. 



(3) Do not have the paraffin in the 

 bath too hot; always have an edge of 

 unmelted paraffin and keep the floating 

 paper boxes close to this unmelted 

 paraffin. 



Explanation of Figures. — (A) Paper 

 cornucopia for containing small objects 

 (IXI). (B) Rectangular tin-box con- 

 taining paraffin and resting upon a tri- 

 angle at the smaller end of which the 

 gas jet is applied (1X7). (C) Rectangu- 

 lar paper boxes for holding objects while 

 in the paraffin bath (1x1). (D) Diagram 

 for folding paper to make paper boxes 

 for holding objects while in the paraffin. 

 Frank Haines Lamb. 



Leland Stanford, Jr., University. 



The Methylen Blue Method for 

 Staining Nerve Tissues. 



G. Carl Huber, M. D. 



That we have in the past few years 

 made such notable advances in our 

 knowledge of structure of the peri- 

 pheral nervous system — peripheral 

 nerves, sensory and motor endings, 

 special senses, sympathetic and spinal 

 ganglia — is in a great measure due to 

 the fact that we have in methylen blue 

 a stain which, when used under certain 

 conditions, brings out these structures 

 most clearly. It is not my purpose to 

 review historically nor even critically 

 the now somewhat voluminous literature 

 bearing on this method, which, since its 

 introduction by Ehrlich in 1885, has been 

 used by so large a number of investiga- 

 tors, but rather to give briefly the 

 methods which in a somewhat extended 

 experience have proven most successful 

 in my hands. I do this, not because I 

 feel that I have materially added to the 

 methods suggested by other writers, but 

 because in using their methods, I have 

 been able to sift them, and retain for 

 my own use the ones which have proven 

 more generally successful. I need, how- 

 ever, add that my observations pertain 

 to such made on vertebrates and more 

 particularly on mammalia. Two 

 methods for bringing the stain in con- 

 tact with the nerve-tissues are now in 



