42 DR. ORD ON THE VALUE OF GLYCEKINE IN MICKOSCOPY. 



solution and precipitation. In later experiments, when the 

 murexide was treated with very strong, slightly acid, glyce- 

 rine, the crystals altogether disappeared after a few weeks, 

 and were replaced by small spherical beads of a purplish- 

 brown colour, very far short in their total bulk of the ori- 

 ginal bulk of the murexide. The little bodies were very 

 uniform in size fabout TrViiTjth inch); Avere sometimes perfect 

 spheres, sometimes intermediate in form between spheres and 

 dumb-bells; were of considerable opacity; and exerted no 

 influence on polarised light. 



At the end of a year these bodies are quite unaltered, and 

 I have just compared them with murexide put up at the 

 same time in Canada balsam, and still perfect as when first 

 preserved. 



On another occasion some crystals of oxalate of lime 

 showing transition from the octohedral to the tetrahedral form 

 were put up, some in Deane's medium, some in glycerine 

 jelly, some in Canada balsam. In a few weeks the crystals 

 in the glycerine jelly were all broken up, and their place was 

 occupied by irregular masses of granular matter, and by 

 dumb-bells and other sub-spherical bodies. The crystals in 

 the Deane's medium, at that time still perfect, followed suit 

 during the next few months, and at the end of three years 

 the balsam also was found to contain no crystals, a few dumb- 

 bells being scattered among formless matter. Here what was 

 effected by the other media in months or years was for gly- 

 cerine the work of only a few weeks. 



More recently I liave tried to turfl this transforming power 

 of glycerine to definite use, and have seen it in several in- 

 stances intensify the power of colloids to break down crystals 

 and mould their substance into spheres. Triple phosphate, 

 for example, resists the action of such a colloid as gelatine, 

 in so far that, while it rarely takes the " house-top" form, 

 it on the other hand goes no nearer the sphere than to be 

 gathered into large lumps of irregularly radiating stalactitic 

 crystals, still perfectly sharp at their points and edges. Gly- 

 cerine being added, much smaller aggregations are produced — 

 either spherical, two-lobed or grape-bunch-like bodies with 

 strongly marked internal fibrous radiation, or tufts of radiating 

 spicules of uniform length ; and with these are mixed some 

 of the stalactitic lumps with their edges rounded and lost. 



With such evidence of the alterative power of glycerine 

 before us, it is impossible not to feel some misgivings as to 

 the results of its use in the preparation of tissues for the 

 microscope. Dr. Beale, who has probably used glycerine 

 more effectively than any other observer, has shown me 



