Ill 



excej^t by means of sections. This may apj^ly to whole plants, as 

 in the case of cu^shion plants, BalanophoraSj or to peculiar stems, 

 as those of cacti or cactoid Euphorbias, or to tubers^ rhizomes, and 

 bulbs, or to large fleshy flowers, or, and this is most often the 

 case, to large fleshy fruits. It ^vould be best to jDreserve such fruits 

 by the wet method, but it is probable that, as a rule, some 

 method of drying will have to be resorted to wherever the struc- 

 ture is sufficiently strong to prevent a complete collapse. In 

 many cases mere exposure to the sun or over fire will be suffi- 

 cient, but to avoid distortion and rupture the drying must not 

 be forced. In certain cases, however, the fruits will dry so 

 slowly that decomposition or destruction by insects in the inner 

 parts of the specimen may occur. In these circumstances immer- 

 sion in spirit previous to drying will generally accelerate the 

 process and also destroy any fungus germs or insects that raaj be 

 present. It may be found advisable to prick and also to divide 

 any object immersed in spirit. The drying in air should not be 

 carried so far as to make the specimens too brittle or too hard. 

 In fact, in not a few cases it will be found that the specimens 

 have when half -dry become sufficiently tough and reduced in 

 bulk to be pressed without harm. This applies also to Agarics 

 and similar fungi which cannot be laid into the press when fresh, 

 nor preserved with advantage in fluids. They liave to be slowly 

 dried in the sun or over fire until thev are tough enouo-h to be 

 pressed gently, and a short bath in spirit before pressing will be 

 useful in order to destroy any grubs or insects in them. 



B. The wet method. — There will always be a few objects which 



dry 





in air, since their soft structures will lose so much of their 

 natural shape and consistence that they will be useless for subse- 

 quent examination. Such objects will have to be preserved in a 

 suitable fluid, and this also applies to specimens which are 

 intended for minute examination. 



The fluids which can be used are Alcohol, Formaldehyde or 

 Formol, and strong solutions of common Salt in water. 



«. Alcohol, — Alcohol, if '' proof '' spirit*, should be diluted by 

 adding 1 volume of water to each volume of spirit, as the speci- 

 mens would otherwise become too brittle and would suffer in 

 transport. 



h. Formaldehyde. — This fluid has the same preserving pro- 

 perties as alcohol, but the objects may get too soft if left long in 

 it. On the other hand, it has this advantage over spirit, that tlie 

 same volume will go much farther. Commercial formaldehyde is 

 a 40 per cent, solution which before use must be diluted down by 

 the addition of water to 4 per cent. In most cases a 2 per cent, 

 solution will be sufficiently s+'rong. A qua,rt of formaldehyde will 

 therefore yield as much preservative fluid as 1 to 2 gallons of 

 spirit. As formaldehyde in solution or in vapour is a strong 





* Proof spirit is alcohol of 50 per cent, strength and ordinary whiskej- is 

 about " proof " strength. For the preservation of specimens alcohol of 20-25 

 per cent, strength is suitable. 



