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study of the brain, nuchal organ, &e.; and horizontal 
sections are almost essential for the study of the nervous 
system, particularly the brain, otocysts, the ventral nerve 
cord, and the giant cells. If sections of certain organs 
only be desired, it is best to procure these from a worm 
chloroformed and opened as soon as it is taken from the 
sand. The organs are excised, separately preserved and 
sectioned as desired. The following parts may be sug- 
gested-—the otocyst, various portions of the alimentary 
canal to show the condition of the gland cells, &e., when 
the gut is full of sand (of course, the sand must be rapidly 
washed out with sea water before preserving each part), a 
nephridium with gonad,* and a heart (one not dilated with 
blood, as when imbedded the blood becomes very brittle 
and impossible to cut). 
Post-Larval Stages. 
These are not readily obtained. Occasionally living 
specimens may be got from Plymouth in March and April. 
These are, of course, best for examination, as some of the 
structures described, such as the processes on the nephro- 
stomes, can only be seen in living specimens. Preserved 
specimens should be lightly stained in borax carmine, and 
examined in cedar-wood oil, so that they may be turned 
over as occasion requires. For preparation of sete cut out 
two or three of the posterior chetigerous segmentst and 
warm gently in a watch glass in 5 per cent. caustic soda. 
Before the muscular tissue is dissolved transfer by means 
of a pipette to water, and later to glycerine. After 
* Whole mounts of the first nephridium, and one or two others 
with their gonads are very useful. Stain with carmine and mount in 
balsam. 
+ From a spirit specimen. If the specimen be in oil remove the 
latter by treatment with absolute alcohol before warming in caustic 
soda. 
