i5° 



HA RD WICKE'S SCIENCE- G OSSIP. 



structure, first starve the rotifer for a few hours in clean 

 water. There are two points which make failure 

 possible. First, the exact quantity to use — this can be 

 acquired by practice alone : use as little as possible. 

 Second, in certain waters a thick deposit is thrown 

 down some hours after the solution is added : the only 

 way to obviate this is to transfer rotifers to fresh water 

 and try again. I have some mounts of Asplaiichna 

 priodotita, as perfect now as when first put up two 

 years since. Seal with Ward's brown cement : this 

 had better be used with all the organisms ; it is very 

 reliable and easy to work. 



Infusoria. — A great deal has yet to be learnt with 

 regard to the preservation of these animalcula, as 

 that which fixes some naturally, is useless with others. 

 For Carchesium and other Vorttcellina : — 



Saturated solution of picric acid. — Apply suddenly 

 when the zoids are extended ; well wash in alcohol. 

 To stain prepare as follows : Alcohol, 75 °/ , 2 oz. ; 

 hydrochloric acid, 4 drops ; carmine, 3 grains. Boil 

 this preparation slowly for ten minutes ; when cold, 

 filter. If the stain shows a tendency to yellowness, add 

 one or two drops of ammonia, until the right colour is 

 restored, and filter again. After staining wash out 

 excessive stain in acidulated alcohol, then transfer 

 through absolute alcohol and cloves to balsam. The 

 transference into the cloves must be carefully done, 

 or great shrinking will take place ; introduce a few 

 drops of oil of cloves into the bottom of a precipitating 

 glass containing the alcohol, and let the stained 

 infusoria gravitate into the cloves, then withdraw the 

 alcohol, add a little more cloves, and transfer into 

 balsam. Picric acid will not satisfactorily kill Para- 

 mecium, Urostyla, etc. 



Salicylic vinegar.— Pyroligneous acid, 100 parts ; 

 salicylic acid, 1 part. This will be found the most 

 generally useful. It kills such forms as Paramecium, 

 Coleps, Spirostomum, Stentor, etc., and certain 

 Vorticellie fully extended, and can be used as a 

 mounting medium. 



£ Saturated solution of bichloride of mercury. — Very 

 useful for fixing Paramecium, Urostyla, etc., but 

 generally causes Vorticellae to contract. Great care 

 must be taken to wash away every trace before 

 mounting. 



The efficacy of all the foregoing solutions largely 

 depends on the particular medium used being applied 

 suddenly and in a concentrated form. By that I 

 mean, have as little water surrounding the infusoria 

 as possible. 



Osmic acid. — Very useful at times, applied as a 

 vapour. Put drop of water with infusoria on cover 

 glass, and hold over mouth of bottle containing osmic 

 solution. A drop applied to water containing any 

 Tentaculifcra fixes them most satisfactorily. Care 

 must be taken not to use too much, or they will 

 become blackened and useless. 



I have never got very good results from potassic 

 iodide or perchloride of iron solutions. 



Entomostraca and small larvae can be fixed with 

 bichloride of mercury ; and, after being thoroughly 

 washed, mounted in Nolls' medium, as under : 

 Salicylic vinegar (as above), I vol. ; dilute glycerine 

 (glycerine I vol., water 4 vols.), 10 vols. ; Farrant's 

 medium, 11 vols. This is generally a most useful 

 fluid to keep by one, but does not answer where the 

 integument of the object is very chitinous. 



Vermes. — Picric acid solution, or bichloride of 

 mercury ; either fixes admirably. 



Hydr^e. — Put a Plydra into watch-glass with as 

 little water as possible ; when it is fully extended 

 add suddenly bichloride of mercury solution ; well 

 wash and mount in Nolls' medium. 



Hydrachnea. — These may be splendidly pre- 

 served by putting them living into a cell containing a 

 saturated solution of boro-glyceride, and sealing the 

 mount down. The animal will probably live in this 

 for a day or two, and then will be perfectly preserved 

 in form and colour. 



Alce. — A few drops of saturated aqueous solution 

 of salicylic acid added to the water containing them 

 will preserve Volvox (showing cilia), Spirogyra, with- 

 out contracting chlorophyll spirals, etc. Use very 

 little of the solution, otherwise it will bleach. 



I may remark that I have in my cabinet mounts of 

 all the forms referred to, preserved in the way men- 

 tioned, and I should be very glad to see through the 

 pages of Science-Gossip any other hints as to the 

 preservation of pond organisms, but more particularly 

 the Rotifera and Infusoria. 



THE POISONOUS PROPERTIES OF THE 

 YEW. 



SEEING that, according to a note in the June 

 issue of Science-Gossip (page 142), there still 

 remains some uncertainty, not to say ignorance, as 

 to certain characteristics of the yew, I am induced 

 to offer a few notes on the subject. 



The yew, Taxus baccata, or English yew, is 

 sufficiently well-known, and need not be described. 

 The Irish yew, Taxus fastigiata, differs slightly with 

 regard to the leaves, and considerably as to the 

 general appearance of the tree. The wood of the 

 yew is tough and hard, and is now chiefly used for 

 cabinet-work. 



That the leaves of the yew contain a principle 

 which renders them poisonous was a fact well-known 

 to the Greeks and Romans, although they were of 

 course ignorant of the nature of it. The researches 

 of modern chemistry show that there is an oleo-resin 

 in them, which can further be split up into a volatile 

 oil and an amorphous alkaloid, to which the name of 

 taxine has been given. This oleo-resin is insoluble 

 in water, hence the strained decoction of yew-leaves, 

 or yew-tea, has no medicinal effect, although it is 



