448 Andrews: Preservation of protoplasinic spinnings. XIV. 4. 



in preservation of these protoplastic processes. In 1894, while at 

 Prof. Lacazb Duthier's Laboratory at Roseoff, France, I repeated 

 and modified tbem. Trial was tirst made of picro - sulphuric, picro- 

 acetic, corrosive Sublimate, Hallee's fluid, Flemmixg's fluid, and 

 Perenyi's (all of these botli bot and cold); also of bot water for killing, 

 and of other reagents tliat happened to be at band. All of these 

 were more delicately and carefully used than is common, the effects 

 on sonie control eggs being in most cases watched ander the micro- 

 scope during fixation. 



None of the above reagents proved good for my purpose. 1 

 Some show of sueeess, however, was gained with a killing and 

 hardening method I had found good in temporary preservations of 

 Protozoa, and also of some rotifers' eggs. Bütschli notes a similar 

 method, as favorable for bringing out bis special vesicular structure. 



No less than fifty trial experiments were made with tbis method 

 at each Station, those at Roscoff being bettered by experience and 

 thought, and variouslv modified in different instances. 



The method which succeeded liest, so far as I had time to 

 develope it imperfectly, was as follows. The fumes of two per cent 

 osmic aeid Solution were concentrated by heat in a glass Chamber. 

 For this I used a Large closed tube wbose base rested on eaeb side 

 on a glass slide, leaving just space enough in the center for a 

 third slide to be slipped in and out. The wbole stood on a glass 

 plate, and was kept on a water bäth to maintain as even a tem- 

 perature as possible. The central slide carried a watch glass of 

 osmie Solution, whose ingress and egress was provided for by an 

 opportune broken place in the glass tube, the clösely fitting frag- 

 ment being beld in place between whiles by a rubber band. When 

 the osmic fumes were sufficiently concentrated, aecording to my 

 judgment in a given instance , the central slide was displaced by 

 another ot like size. On tbis the eggs had been quickly arranged 

 at the previous moment, in a Single layer, as compactly as possible, 

 with only enough water to cover tbem. Tbc dift'erence afforded by 

 eboiee of a slightly tbinner slide permitted the eggs to ]iass linder 

 the tube-wall into the Chamber, and a couple of fragments of slide 

 placed across the ends sealed the Chamber sufficiently tbere. After 



1 1 Wlnle I am not sure of having fully tested the usefulness for 

 tbis purpose of these reagents, it is certain that, as used by nie then, they 

 did not sueeeed at all. 



