1896 THE MICROSCOPE. 73 



may be removed for study mucli longer after death than 

 in any other way known to me, at the same cost of ma- 

 terial and time. 



The advantages of formalin in the lines discussed above 

 may be summarized briefly thus : It is cheaper than any 

 other method that gives good results; it gives results in 

 much less time ; the colors are better preserved and there 

 is less change of form by shrinkage or by swelling; its 

 penetrating power is excellent so that insects, Crustacea, 

 etc., preserved in it are fit for work on the internal or- 

 gans ; for moUusks and vermes it is also excellent. 



Its disadvantages should likewise be stated. It is ex- 

 tremely volatile and the jars have to be sealed with care. 

 I have not had it in use long enough to decide how great 

 an obstacle this will prove in the museum. Again, the 

 water solution will freeze and not all museums are at all 

 times above 0°C. In such cases, if not in all, hardening 

 in formalin and transferring to the lowest per cent alco- 

 hol that will preserve would seem to be the better and 

 cheaper way. I have not yet had the opportunity to dem- 

 onstrate to Avhat extent preparations thus preserved may 

 be treated to additional alcohol to replace that lost by 

 evaporation, without a precipitate. 



II. Experiments with formalin for histological purposes 

 were undertaken in February last. The visceral organs 

 of Gryptohranchiis were placed while perfectly fresh in a 

 suitable solution of borax carmine with five per cent for- 

 malin; the third day the pieces were washed, the stain 

 fixed and dehydration in sixty per cent alcohol com- 

 menced ; they were passed rapidly through alcohols of 

 increasing strength, and the end of seven to ten days 

 were infiltrated with paraffin and ready to cut. The 

 liver, intestines and kidney were sectioned, leaving no- 

 thing to be desired in stain or character of the cells. 



Parts were at the same time hardened in five per cent 



