138 SUMMARY OF CURRENT RESEARCHES RELATING TO 



examined (periosteum, tendon, &c.) a 4 per cent, solution warmed to 

 50° C is preferable. In this the bones are decalcified. The pieces are 

 next placed for 5-15 minutes in Miiller's fluid, and then in the following 

 silver-glycerin solution : — 2 grm. of silver nitrate are dissolved in 3 ccm. 

 of distilled water; to this are added 15-20 ccm. pure glycerin. Herein 

 they remain for 24-48 hours. On removal they are quickly washed 

 in distilled water and then transferred to alcohol ; therein the excess 

 of silver nitrate is removed. The preparations may be kept in spirit 

 for any length of time. Sections are made under alcohol. In order to 

 prevent any harm from the action of light the sections are immersed for 

 a short time in a 3/4 per cent, solution of salt, and from this at once 

 transferred to absolute alcohol for dehydration. They are cleared up in 

 creosote and mounted in balsam. 



Solvent for the Gelatinous Envelope of Amphibian Eggs.*— Dr. 

 C. 0. Whitman has found hypochlorite of sodium an excellent solvent for 

 the gelatinous envelope of the amphibian egg. He obtained a 10 per 

 cent, solution, and diluted it with five or six times its volume of water. 

 The eggs are first hardened by heating or by immersion in some pre- 

 servative fluid, then placed in the Labarraque solution until the 

 gelatinous envelopes are so far dissolved that the eggs may be easily 

 shaken free. They are then washed and preserved in alcohol. This 

 method works perfectly with the eggs of Neciurus, and has given equally 

 good results with the eggs of the frog. The time required for dissolving 

 the envelope in the case of Neciurus is about five minutes. Care should 

 of course be taken not to leave the eggs exposed to the solvent longer 

 than is necessary in order to destroy the envelope. 



Method of Examining Fragaroides.j — M. C. Maurice gives the 

 following account of the methods adopted in his study of this Ascidian. 

 He found that, owing to the presence of transverse muscles in the gill, 

 the creature contracted too suddenly when treated with picrosulphuric 

 acid, and he used, therefore, the acetic acid method of MM. Van Beneden 

 and Julin. Pure glacial acetic acid (crystallizable) must be used. The 

 colonies were plunged into it entire, and remained there for from 2 to 5 

 minutes, according to their size. They were then placed in 70 per cent., 

 90 per cent., or even absolute alcohol at once. By this means the 

 natural appearance was completely preserved. Specimens of which 

 sections were to be made were placed in borax-carmine for from 15 to 

 18 hours, for it was necessary that the red coloration of the nuclei 

 should be very intense. They were next cleared with hydrochloric acid 

 and washed with 70 per cent, alcohol till the acid had all disappeared. 

 They were then placed in an exceedingly weak solution of Lyons blue 

 made with 70 per cent, alcohol. After remaining in this for from 15 to 

 20 hours, and being shaken two or three times, they were fixed in 

 paraffin in the ordinary way. 



Preparing Fresh-water Bryozoa.J — Although it is not easy to pre- 

 serve Bryozoa in the extended condition, Herr M. Yorworn claims to 

 have obtained excellent results with Cristatella by means of a 10 per 

 cent, solution of chlorai hydrate. The colonies were placed direct 

 in this solution, and though at first they became contracted, they 



* Amer. Natural., xxii. (1888) p. 857. t Arch, de Biol., viii. (1888) pp. 220-3. 

 % Zeitschr. f. Wiss, Zoo]., xlvi. (1887) p. 99 ( 2 pis. and 9 figs.). Cf. this Journal, 

 1888, p. 27. 



