1884] Microscopy and Histotogy. 1291 
THE ORGANIZATION OF THE EcHinoruyncul.!'— 1. Method of 
Preparation —It is a very difficult matter to kill Echinorhynchi 
instantly. This cannot be done either with corrosive sublimate or 
strong osmic acid, even after preliminary treatment with tobacco 
smoke or chloroform. Thus treated, they contract strongly, and 
remain so after death. 
Much the best results are obtained by killing gradually with 0.1 
per cent osmic acid, in which they contract during the first hours, 
but stretch out again and die fully extended. This method causes 
slight swelling, but does not seriously injure the object for histologi- 
calinvestigation. Inspecimens left for twenty-four hours in the osmic 
_ acid, it is easy to isolate under the dissecting microscope the sub- 
cuticula, and the two layers of muscle-fibers (circular and longi- 
tudinal). For the study of the internal organs, the Echinorhynchi 
should be cut open immediately after death and transferred to a 
0.01 per cent solution of osmic acid. The preservation of speci- 
mens thus treated may be accomplished in the following manner: 
After carefully washing away the osmic acid, place the objects in 
avery dilute solution of potassic acetate in an open vessel, and 
leave them for two or three days, during which much of the solu- 
tion evaporates. Finally transfer to a saturated solution in order 
to clarify so far as possible. Very beautiful preparations are said 
to be thus obtained. 
The course of the nerves may be easily traced in specimens that 
have lain several days in 1 per cent formic acid. The tissues swell 
up strongly and become quite transparent so that the nerves can 
be seen. If the muscular layers be separated from the subcuticula 
in specimens thus treated, and then stained in gold chloride, the 
lateral nerve-trunks may be clearly shown. For the histological 
study of the nerves, the Echinorhynchi should be treated with 
chromic acid and then stained deeply with borax-carmine. 
romic acid preparations are also best for the study of the 
subcuticula. Echinorhynchi live for days in a one-tenth per cent 
Solution of chromic acid, but eventually die in a fully extended 
condition. Such preparations, after treatment with alcohol, may 
colored at once; or, after washing a day or more in running 
- Water, exposed to the action of osmic acid, and then colored in 
mine. : i ae 
For the study of the sexual organs, a very dilute picro-sulphuric 
- acid (one part of the acid to eight-tenths part of water) is recom- 
end 
The tissues of the Echinorhynchi are not easily stained. Borax- 
i according to Sæfftigen, is the best staining fluid, 
must be allowed to act a long time (often one or more days); after 
_ deep stain has been taken, the preparation should be partially 
TA. Seftigen, Morph. Fahrb., X, Heft 1, pp. 120-163, 1884. 
