Strong, Review of the Gotgi Method. 1 1 3 



yellow (owing to a second impregnation which takes place), 

 then the outline of the stained cell elements become obliterated, 

 the whole tissue becomes opaque and, after a period of from 

 two or three months to two years, the preparations, with few 

 exceptions, become useless. On the contrary they may keep 

 a long time thanks to the repeated washing, of which I have 

 spoken, and especially to the mode of mounting without a cover 

 slip in a layer of damar. I can now state that the earlier la- 

 mentable disadvantage that preparations made by my method 

 soon spoiled is now almost completely remedied. I have many 

 preparations made by me nine years ago which have not yet lost 

 their original clearness. 



" If the good preservation appears menaced by an incipi- 

 ent yellowing, another longer bath, on the slide, in turpentine 

 will restore transparency and freshness to the preparation. 



**I have found it convenient to employ for this kind of 

 mounting a special wooden slide with a square opening in 

 which, by means of a groove, a glass plate (a cover slip of 

 somewhat greater diameter than usual) is fitted and stuck fast 

 with a solution of shellac in alcohol. This serves as a slide and 

 the section adheres to it by means of the damar. 



"This kind of slide not only enables the section to be ex- 

 amined from both sides but also has the advantage of prevent- 

 ing dust from fouling the object, to which this kind of mount 

 would be especially exposed. To accomplish this it is only 

 necessary to turn the side of the slide with the section down- 

 wards as soon as the damar is hard enough, or to pile the prep- 

 arations on top of each other. 



"I further remark that it is wise to shield the objects 

 from the influence of light ; still this precaution is not entirely 

 necessary if the repeated washing has been carefully performed. 

 After fulfilling these conditions, I might expose preparations 

 for days to the sun's rays without injury to them. 



" This is not the place to lay stress upon the value of the 

 results which can be attained by means of this method. The 

 figures accompanying this work demonstrate it sufficiently. 

 They display the forms to be observed in the preparations with 



