OF THE STIPITATE DIATOMACE^. 



35 



the unavoidable removals from the herbarium, or from any 



accident to the papers in which they are contained. The 



safety of the Diatomacese is best 



secured by making the envelope 



of the form annexed, fig. 43. The 



slide with its deposit is laid on 



the square, 5, face upwards. The 



upper square, a, is carefully folded 



over it, and the double square 



thus formed is again folded over 



the lowest part, c. The two wings, 



d, e, being successively bent over 



the whole, prevent the glass from 



falling out at the sides. 



Should the plants be of a pecu- 

 liarly delicate nature (as is gene- 

 rally the case where they have 



been subjected to the action of an acid), it is a good plan to 

 gum a strip of cardboard on each side of the central mass, 

 a, b, fig. 44. Upon these a loose piece of glass may be laid 

 whenever the specimens are put away, which may be taken 



Fig. 44. 





Fig. 43. 







a 







I 





d 



c 



e 



off when the latter are required for examination. I am not 

 sure that this arrangement of the covering glass had not 

 better be the general rule with beginners, instead of the 

 exception, because it ensures the safe keeping of the en- 



closed Algae. 



d2 



