2 
Siphonophora Rosarum 
comparative work, to obtain a somewhat more complete account of the 
general anatomy. It is with this idea in view that the following paper 
has been written ; but, as will be seen on perusing it, much more 
attention has been given to the internal anatomy than to the external 
parts. It is my intention, now that this first part of the task is 
completed, to take up my original project. I desire to take this 
opportunity of expressing my gratitude to Professor Bridge, Mr 
A. E. Shipley, F.R.S., Mr Doncaster and Mr Collinge for the valuable 
assistance and advice they have given me whilst this work has been in 
progress. 
Methods. 
The extremely small size and delicacy of the insects dealt with 
entailed somewhat careful manipulation. To obtain a good supply of 
material, rose trees were infested, as far as possible, with S. rosarum 
only. In this way a fresh supply of good material was always ready at 
hand. For fixing, Petrunkewitsch’s modification of Gilson’s fluid was 
used, the formula being: 
Water (distilled) 30 parts. 
Absolute alcohol 20 parts. 
Glacial Acetic Acid 9 parts. 
Nitric Acid (pure) 1 part. 
Corrosive sublimate to saturation. 
For staining the sections, Naples Carmine, Ehrlich’s Haematoxylin, and 
Weigert’s Elastic tissue stains were used. 
In order to confirm results obtained from the serial sections 
dissections were made; and for this purpose I found the large binocular 
dissecting microscope made by Zeiss of the utmost use. The microscope 
was the one having the alterations suggested by Braus and Drfiner, and 
the large working distance possessed by its lenses gave great facility in 
work performed under it. The instrument is to be strongly recom¬ 
mended for such minute work as the dissection of Aphides. The 
dissections were carried out in glycerine. 
Whilst engaged on the tracheal system, I found that a very 
effective way of showing up the details of the system was to kill and 
mount a few specimens in hot glycerine jelly. The effect was that the 
jelly in cooling, stopped up the stigmata, preventing the escape of the 
air, and yet penetrating sufficiently to render the animals transparent. 
Care must be taken not to overheat the jelly, or the heat will drive the 
