Beook : Summary of Methods of Miceoscopical Eesearch. -45 



objects or of smaller whole ones, should be transferred to oil of cloves 

 before proceeding to the minute dissection. The objects being more 

 transparent, it is easier to carry on the work in this medium than in 

 alcohol. The brittleness which is caused by oil of cloves is in most 

 cases advantageous, but can easily be reduced by the addition of 

 creosote. The tendency to collect in small drops, which is peculiar 

 to oil of cloves, may be counteracted by the addition of oil of 

 bergamot. 



Imbedding Methods. — Imbedding, for section cutting, is usually 

 done in paraffin, either pure or mixed with lard. Instead of the latter, 

 however, one often uses a paraffin, which in summer time becomes 

 soft, on account of its containing liquid hydrocarbons, and is 

 preferable to lard, because it is not liable to become rancid. The 

 imbedding takes place in the usual way, after the object has been 

 passed through a warm bath of paraffin and turpentine, or paraffin 

 and creosote. With a microtome one can always cut dry, and the 

 curling up of the section is prevented by a small spathula, which, 

 without any pressure, is held over the cutting part of the knife. The 

 paraffin is afterwards dissolved out by means of turpentine. The 

 method given by Calberla and Selenka, for imbedding in a mixture of 

 albumen, has not p'l'oved satisfactory. Tissues which have been 

 preserved in alcohol, suffer greatly by being transferred to albumen 

 and water, or even to pure albumen. 



Gelatine is a convenient imbedding medium, and Dr. Mayer has 

 devised a process by which it can be deprived of its tiresome elasticity. 

 The gelatine is allowed to soak, as usual, in water, then it is heated, 

 and 1 to -i a volume of castor oil is added ; shake well, and shortly 

 before getting cold, pour the mixture into a bowl. When, afterwards, 

 all the castor oil has been extracted by 90% alcohol, the gelatine 

 remains as a fine porous matter, a sort of artificial pith, and is at once 

 ready for use. Naturally, it must not be exposed too long to the air, 

 as this would soften it. Under the microscope, this form of gelatine 

 is less troublesome than lilac pith, and has the advantage that it can 

 be produced in any size, and always even. 



A PHYSIOLOGICAL ARRANGEMENT OF LEPIDOPTERA. 

 By a. H. Swinton. 



It has been a long standing practice with authoi'S of works on 

 British Butterflies to treat of the five groups represented in this 

 country in the following order : Papilionidcs, Nymphalida, Erycinidce^ 



