Journal of 



Applied Microscopy. 



Volume II. OCTOBER, 1899. NumbeiI 10 



Formalin as a Preservative for Botanical Specimens. 



The enormous strides that have been made in botanical teaching in the last 

 few years have suggested opportunities for displaying material, by means of which 

 many morphological, physiological, pathological, and ecological characteristics 

 of plants may be shown. The older type of botanical museums, where a hetero- 

 geneous, unclassified mass of curious material is associated together, is of little 

 importance other than that of a curiosity shop. To meet modern demands the 

 collection need not, however, necessarily be a large one, but it should at least 

 teach something and should be situated in the laboratory or lecture room, or 

 close to it, where, if necessary, it may be easily made use of for purposes of 

 illustration in the class room. In short, a collection of this nature constitutes a 

 pedagogical collection, and it is much more valuable in aiding the modern 

 methods of teaching botany than the primitive collections which many old 

 botanical institutions now possess. 



The writer, however, has a primitive collection at his disposal which has 

 never been of any use in class work, and for this reason we have endeavored to 

 build up a special collection for purpose of illustration in Morphology, Phys- 

 iology, and Pathology, and as considerable attention has been given to preparing 

 and mounting the specimens, a brief description may be of interest to botanists. 



In the preparation of specimens we have made use of formalin, which, as a 

 preservative, greatly excels any other solution as a means of displaying 

 botanical specimens. The writer has used formalin in his laboratory for six 

 years, for a great variety of purposes, with results that could not be obtained by 

 the use of any other preservative known to him. 



The strength of the formalin solution used for preserving specimens is four 

 (4) parts of the forty per cent, solution to one hundred (100) parts of water. 

 Two to three parts to one hundred have been tried, but solutions of these pro- 

 portions have not proved satisfactory. 



Most of our specimens have been kept in a 4-100 parts solution for five years 

 without renewing, and with the exception of a slight tendency to form a precipi- 

 tation in some of the jars, they are as clear as ever. The specimens are kept in 

 both round and rectangular jars of glass, but we prefer the round jar of even 

 texture and of good quality to any other, inasmuch as the slight magnifications 

 of the specimen in such a jar we consider an advantage. 



(537) 



