1889.] Microscopy. 189 
Central Nervous System of Lumbricus.' — If the 
earthworm is to be sectioned in toto, it is necessary to remove 
the sand from the alimentary canal. For this purpose, place 
the worm in a glass cylinder partly filled with fine bits of wet 
filter-paper. As the paper is swallowed the sand is expelled, 
and at the end of about two days the alimentary tract is 
In the study of the ventral cord, Friedlander employed the 
following methods: 
Place the worm in water, to which a little chloroform has been 
added, and it soon becomes stupefied in an outstretched con- 
dition. Then cut open the body-wall along the median dorsal 
line, and pin the edges down in a dish covered with paraffine 
or wax. After removing the alimentary canal, the specimen 
may be treated with a preservative fluid. 
1. Osmic acid \%. Aftfer an exposure of about half an 
hour, the worm is sufficiently stiffened to allow the pins to be 
removed, and it may then be cut into pieces of any desired 
length. The pieces are then left twenty-four hours in the 
same solution, then washed, and passed through the usual 
grades of alcohol. Preparatory to embedding in paraffine, the 
pieces are saturated with chloroform or toluol. This method 
is excellent for the study of the neuroglia-like elements, and is 
the best for the brain. 
2. Preparations treated thirty minutes M'ith osmic acid (1%) 
are transferred to a dilute solution of pyroligneous acid (i part 
to three parts water), which reduces the osmic acid very quick- 
ly. This is followed by alcohol as before. The ganglion cells 
are well preserved. 
3. The preparation is first treated with weak alcohol, then 
with stronger grades. After half an hour in 70% alcohol, it 
IS stiff enough for removing the pins, and for cutting into 
small pieces. Nerve fibres are somewhat contracted by this 
method, and are thus more easily distinguished from the sur- 
4- Corrosive sublimate (aqueous sol.) and 50% alcohol in 
equal parts (thirty minutes) gave good preparations of the 
nerves and the neural tubes. 
For preparations according to No. 3, the best stain is a mod- 
ified form of Mayer's alcohol carmine, absolute alcohol being 
substituted for 80%. Sublimate preparations are successfully 
stained with Grenacher's haematoxylin. After half an hour in 
this staining fluid, the preparations are transferred to acidu- 
1 Benedict Friedlander, Zeitschr. /. wiss. Zoologie, XLVII, I, 1888, p. 48. 
