MOUNTING THE SPECIMENS, ETC. 37 



of the varnished lines may be trimmed with a penknife, 

 or some other light instrument, if thought necessary, 

 after the varnish is perfectly dry. 



To mount Algse in Canada balsam, it is not neces- 

 sary to prepare any cells : the object is merely to be 

 laid on the glass slide, in as fresh a state as possible, to 

 insure a proper degree of plumpness and fulness. 

 Though it may be advisable to pass the specimen 

 quickly through clean fresh water, to remove as much 

 of the salt as possible, it must be borne in mind that 

 some plants, such as the Grifnthsiae, will not bear fresh 

 water for an instant. The specimen, after being dis- 

 played with great care, and as expeditiously as possible, 

 is then to be left until all the external water shall have 

 evaporated from its surface, as well as from the glass. 



A bodkin or probe, or any other suitable instrument, 

 is then to be dipped very gently (to avoid air-bubbles) 

 into the Canada balsam, and then withdrawn rather 

 more rapidly. A quantity of the balsam will adhere to 

 the instrument ; and by holding it vertically a drop 

 will be formed at the lower end. The apex of the 

 drop is then to be brought in contact with the specimen, 

 as near the centre as possible. By degrees the drop 

 will detach itself from the instrument, when the latter 

 must be withdrawn. The drop should be large enough 

 to cover the specimen completely after being spread out 

 and properly arranged beforehand, in order to avoid the 



