ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 373 



To this stock-fluid may be added formalin, chromic acid, Fleniming's 

 fluid, osmic acid, &c. 



The stains used are eosin and orange G, 1 grm. each to 200 of 

 distilled water. The preparations are washed in 60 p.c. alcohol, after 

 which they are stained in toluidin-blue, 1 grm. to 200 of water. After 

 decolorising in 60 p.c. alcohol and dehydrating in absolute alcohol, the 

 preparations are mounted in xylol-balsam. 



Fixation of Polychseta Embryos.* — A. Soulier when studying the 

 early phases of the embryology of Serpida, fixed artificially fecundated 

 ova at various stages of maturation with various fluids. Of those which 

 contain osmic acid, Flemming, Fol's, and Cori's proved to give only 

 moderately successful results. Much more satisfactory were the mix- 

 tures known as Gilson's, Roule's, and Eipart et Petit's, Gilson's fluid 

 is composed of nitric acid 78 ccm., glacial acetic acid 22 ccm., sublimate 

 100 grm., alcohol 60 p.c. 500 ccm., distilled water 4400 ccm. Roule's 

 fluid is a mixture of saturated solution of sublimate 80 ccm., and glacial 

 acetic acid 20 ccm. Eipart et Petit's fluid contains chloride of copper 

 0*3 grm., acetate of copper 0*8 grm., glacial acetic acid 1 grm., dis- 

 tilled water 150 grm. One volume of any of these fixatives is mixed 

 with three volumes of sea-water containing the ova. Their use does 

 not necessitate a prolonged washing, and they do not interfere with the 

 action of staining solutions. 



Examining Nervous System of Sipunculus nudus.f — For examin- 

 ing Sipunculus nudus in the fresh condition H. von Mack obtained un- 

 contracted specimens by adding at intervals 75 p.c. alcohol to the sea- 

 water in which the animals were kept. 1 p.c. cocain solution was also 

 very effective. For teasing-out or maceration-preparations Muller's 

 fluid and nitric acid were used. Treatment with the former required 

 several weeks, the tissue being afterwards stained with haematoxylin ; 

 with the latter in 20 p.c. solution 24 hours were sufficient, the pieces 

 being afterwards washed with distilled water for 24 hours and then, 

 having been mordanted with alum, stained with haematoxylin. 



For sectioning pieces of tissue 1 cm. long, several fixatives were 

 used, e.g. saturated solution of sublimate in 0*5-0*7 p.c. salt solution 

 (15-20 hours), or Apathy's sublimate-alcohol (16-24 hours). After 

 either of these, washing in water, then graded alcohols (30 p.c, 50 p.c, 

 70 p.c), and Apathy's alcoholic iodopotassic iodide to 96 p.c. alcohol. 

 This avoids the red precipitate of iodide of mercury which is deposited 

 when the aqueous iodopotassic iodide is employed. Other fixatives 

 used were equal volumes of 1 p.c. osmic acid and the salt-sublimate 

 solution; \ p.c. osmic acid in sea-water; Flemming's mixture and 

 Tellyesnicky's fluid (acetic acid and bichromate of potassium). 



The material was stained en masse in very dilute Delafield's haema- 

 toxylin, in Apathy's haematein solution I. A., and by a combination of 

 the two fluids. The first of these was T V _ 5V 0I the aqueous or alcoholic 

 (30 p.c.) solution of Delafield's haematoxylin. Duration 6-8 days, after 

 which distilled water and then dehydration in absolute alcohol. The 

 Apathy's solution took 5 days ; the pieces being afterwards washed in 



* Mem. Acad. Sci. et Lett. Montpelier, iii. (1901) pp. 1-7 (4 pis.), 

 t Arb. Zool. Inst. Wien, xiii. (1902) pp. 237-33i (5 pis.). 



