244 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Even better than the preceding is a mixture of gelatin and agar, for 
it combines the advantages of both, and can be incubated at 37° without 
liquefaction : — 2 per cent, agar, 5 per cent, gelatin, 2^ alkali albuminate, 
1 per cent, salt, and 1 per cent, pepton, with the necessary quantity of 
water, are gently heated until the constituents are dissolved. After 
neutralizing with 2 per cent, of the soda solution the mixture is boiled 
for two hours in a steam sterilizer, and then filtered through a thin layer 
of cotton-wool into capsules. 
Antiseptic and Disinfecting Properties of Formic Aldehyde.* — 
M. H. Pottevin who has made experiments as to the antiseptic property 
of formol, finds that the number of germs sown in a medium to which 
formol has been added has a definite influence on the result, i.e. the 
prevention of growth, and also the time required for killing the germs. 
The action of the disinfectant is aided by moisture and elevation of 
temperature. Formic aldehyde has also a direct action on diastase, the 
activity of which is diminished or suppressed. Injected into animals 
formol exhibits irritant properties as shown by the necrosis of the 
tissues, but its toxicity is relatively small. As the vapours given off 
by saturated solutions and by the powder of trioxymethylen are noxious, 
disinfection with formic aldehyde requires great caution. 
Dr. P. Miquel discusses the disinfectant properties of formic alde- 
hyde from the practical aspect. By mixing an aqueous solution of 
commercial formic aldehyde (probably a paraldehyde or a mixture of 
formic aldehydes in different conditions of polymerism) of a density 
of 1 * 07 to 1*08 with calcium chloride, so that the resulting liquid has a 
density of 1*20, a fluid is obtained with which linen cloths can be 
soaked ; when hung up these cloths give off the vapour of formic alde- 
hyde very copiously, and if placed in a confined space serve to disinfect 
very actively. For loose articles such as books, bedding, &c., this 
method acts well, but for the disinfection of rooms and large spaces it is 
not applicable. 
Apparatus for the Care and Hatching of Fresh-water Fish 
Eggs.t — Mr. A. T. Holbrook describes an arrangement which for 
laboratory and experimental use has been found to answer all ordinary 
requirements. In addition to the apparatus, nothing is needed except 
a steady supply of tolerably clean cold water, a cool clean room and a 
sink or water escape. The water enters at the faucet A (fig. 40) and 
splashes on the board B ; it is thus aerated and falls into a box con- 
taining a number of filtering partitions. This box is water-tight and 
provided with a set of four flannel filters of different grades of fineness. ! 
All use of metal in the apparatus is avoided, except where necessary, ; 
and then it is covered with paraffin or other harmless substance. The i 
water leaves the filter-box by means of a tube near the top, from which 
it falls on to another board E, being thus further aerated as it falls into 
a rather large dish or trough ; placed in this trough is a bell-jar N, with 
a considerable opening at the top, and with a piece of fine netting 
stretched and held in place across the bottom of the jar by a rubber 
band. At the further end of the trough is placed a siphon F. When 
* Ann. Inst. Pasteur, viii. (1894) pp. 796-810 ; Ann. de Micrographie, vi. (1894) 
pp. 588-95. t Bull. Mus. Comp. Zool., xxv. (1894) pp. 93 and 4. 
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