116 WILLIAM BATESON. 
Nemertines, &c., are usually found still suspended long after 
most of the mud is precipitated. The water should then of 
course be poured off and left to settle separately. The degree 
to which any particular animals required may thus be easily 
separated off from the rest is very great. The disadvantage of 
such a method is that a certain number of larve are sure to be 
broken in the stirring necessary to effect suspension. I have 
little doubt that the larvee which were observed free-swimming 
earlier than stage F were thus liberated from the egg-shell. 
Preservation.—All my specimens of B. minutus were 
obtained from Naples, being very kindly prepared for me by 
Mr. Weldon with picric acid. 
Most of the larve of B. Kowalevskii were placed for 
less than a minute in corrosive sublimate sat. sol. two parts, 
mixed with one part glacial acetic acid, washed with water and 
successively passed through 380 per cent., 50 per cent., 70 per 
cent., and 90 per cent. spirit. On the whole the results 
given by this reagent were the best. The softer parts, however, 
are best preserved in those specimens which were treated with 
Perenyi’s fluid one hour, then 90 per cent. spirit for twelve hours, 
the 90 per cent. spirit being then changed. In the case of 
adults preserved with Perenyi’s fluid, the fluid was changed 
once or twice. 
Osmic acid did not give good results, but probably this was 
due to bad manipulation. The sections were cut in continuous 
series with Caldwell’s automatic microtome. 
List or Papers REFERRED TO. 
1. Acassiz, ALEx.— Hist. of Balanoglossus and Tornaria,” ‘Mem. Amer. 
Acad.,’ vol. ix. 
. Batrour, F. M.—‘ Monograph on Elasmobranch Fishes,’ 1878. 
3. Bateson, W.—“ Early Stages in Dev. of Balanoglossus,” ‘Quart. Journ. 
Mier. Sci.,’ April, 1884. 
4. Hatscnpx, B.—‘“ Stud. tb. Entw. d. Amphioxus,” Claus’s ‘ Arbeiten, 
Wien, 1881. 
5. Hatscnek, B.—“ Mitth. ib. Amphioxus,” ‘ Zool. Anz.,’ Sept. 29th, 1884. 
iS) 
