634 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Preparation of Nervous System of Hirudinea.* * * § — Dr. E. Bolide 
investigated the nervous system of Aulostomum by means of teased pre- 
parations as well as of sections. The latter were generally prepared 
after hardening in sublimate ; the living animals were forcibly extended 
and fixed in a small vessel containing wax ; an opening was made 
along the dorsal middle line; the worms were covered with a one to two 
per cent, solution of sublimate and left for several hours. After this 
was removed they were gradually put into strong alcohol. Only after 
they had been for a day in 80 per cent, of alcohol was the nervous 
system taken out, stained, and imbedded in paraffin. The author 
strongly recommends this method. Of Pontobdella serial sections only 
were made. Mayer’s alcoholic carmine solution is highly praised as a 
staining reagent, but Golgi’s method is found to be useless for Invertebrata. 
The sections were generally 1/200 mm. thick, but for the recognition of 
the finest structural relations much more delicate sections were necessary. 
The sections were always put in glycerin ; resinous media are to be 
avoided as they make the preparations too transparent for very fine work. 
Mayer’s picric glycerin mixture was found to be of no use, but 
salt solution was useful. 
Mode of Investigating Sipunculus nudus.t — Mr. H. B. Ward at- 
tempted to kill his specimens in such a way as to prevent distortion and 
to preserve well the tissues ; the thick impermeable cuticle and the 
wealth of muscular tissue made the operation one of some difficulty. 
Specimens were allowed to remain for some time in clear sea-water 
so as to get rid of adhering sand ; they were then brought into a shallow 
dish of sea-water, and 5 per cent, alcohol was allowed to flow gently 
over the surface ; the spirit must be allowed to disseminate gradually. 
Narcosis varies with individuals, but supervenes in from four to eight 
hours. When the animals make no contractions on being gently probed 
with a dull instrument they may be regarded as sufficiently stupefied, 
and be transferred to 50 per cent, alcohol. After a short stay in this 
the introvert was cut off, and alone subjected to stronger alcohol. 
Material thus preserved may be well stained by all methods. 
Development of Hydra.J — Dr. A. Brauer, in his study of the de- 
velopment of Hydra, preserved the shell-less eggs chiefly in Flemming’s 
solution, and those that retained their shells by treatment with hot 
corrosive sublimate. The yolk-granules were distinguished from the 
nuclei by double-staining with borax-carmine and malachite-green ; and, 
later, as the nuclear stain was found to be too faint, shell-bearing eggs 
were alone so treated, and the others were put for twelve hours in 
Grenacher’s haematoxylin and washed with acid alcohol. Paraffin was used 
as the imbedding material ; for sections the older shelled ova alone gave 
difficulty ; for these Heider’s mastic-solution was used. 
Study of Karyokinesis in Paramcecium.§ — In the study of Para- 
mecium , Prof. B. Hertwig made use of picro-acetic acid, chromic 
* Zool. Beitrage, hi. (1891) pp. 1-3 and 49-51. 
f Bull. Mus. Comp. Zool., xxi. (1891) pp. 144-5. 
t Zfcitschr. f. Wiss. Zool., lii. (1891) p. 170. 
§ Abhl. d. K. Bayer. Akad. d. Wiss., ii. Cl., xvii. Bd., i. Abtli. (1889) pp. 4-5. 
