114 Transactiojis of the [Sess. 



a finely divided state. In this finely divided state the cloud of 

 ether impinges npon the zinc plate H. From this plate it rapidly 

 evaporates, and in so doing causes the plate to become so cold 

 that it is capable of freezing any moderately sized tissue which is 

 placed upon its upper surface. It is found in practice that at an 

 ordinary temperature (about 50° Fahr.) a tissue about \ inch in 

 diameter and \ inch thick may be frozen in two minutes by the 

 expenditure of \ oz. of ether. The body of the instrument may be 

 briefly described. The framework is of J-inch oak, and consists of 

 a base, A, with two uprights, B B, screwed upon it. The base is 

 bored, to allow the tubes D — for raising the section — to pass 

 between the parallel uprights, and has a projecting part, so as to 

 permit the instrument to be clamped to the table M'. Upon the 

 top of the upright pieces, B B, are cemented two plates of glass, 

 C C. These plates allow the section-knife to move easily along 

 their upper surface, and are so arranged that the knife in its middle 

 part will not touch anything but the tissue. The method of rais- 

 ing the section-plate is as follows : Two accurately fitting brass 

 tubes are taken, and into the outer one, D, the nut, F, of a 

 fine screw is firmly soldered at its lower end. The inner tube has 

 the section-plate fixed to its upper end by two short brass pillars ; 

 between these, however, two small vulcanite washers are intro- 

 duced, so as to prevent the heat of the body of the instrument from 

 being communicated to the section-plate. The milled head, G, 

 pushes the inner tube and accompanying plate, H, gradually 

 upwards. The instrument is the invention of Mr Charles Cathcart, 

 M.B., Lecturer on Anatomy in Surgeon's Hall, Edinburgh ; while 

 my connection with the matter may be seen from the description 

 published by Mr Cathcart in the ' Journal of Anatomy and Physi- 

 ology' for April of this year (1883). 



XVIII.— NOTES ON SPRING VEGETATION AS OBSERVED 



AT MORNINGSIDE. 



By Mr GEO. L. BROWN. 



{Bead March 22, 1883.) 



After returning home from our first excursion for the season, when 

 we visited the Snowdrops at Arniston, it was suggested to me by 

 our Secretary that I might offer a few remarks on Spring Vegeta- 

 tion for the current month at our next meeting, together with as 

 many specimens of different species as might be in flower in Mor- 

 ningside district, but more particularly those plants which, under 

 my own personal care and superintendence, I love to cultivate and 

 minister unto. 



