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The author then called attention to the formation of 
verdegris on insect pins, in old Entomological collections. 
This substance makes its appearance where the pins pass 
through the thorax of the insects, and in leiigtli of time 
grows into a considerable mass of fiocculent matter, of a 
brilliant green colour, and often breaks up the insects and 
also destroys tlie pins. It consists mainly of acetate or 
formiate of copper in combination with fatty or oily matter- 
On examination of various specimens under the microscope, 
they were found to present a great variety of forms, filamen- 
tous and ribbon-like structure, often resembling various 
fungi, in some cases so nearly, that it was difficult to believe 
that the fibres and fruit-like forms are not really organic 
bodies. 
Drawings, and specimens under the microscope, were 
exhibited, and the author expressed his opinion that these 
bodies were simply crystals, modified in their formation by- 
the oil contained in the insects, with which the crystals is 
in some way combined. Some of the specimens exhibited 
were taken from insects collected twenty-five years ago. 
An interesting discussion followed the paper, in which 
the Chairman, Mr. Plant, Mr, Rogers, and other members, 
took part. 
