OX THE DEVELOPMENT OF LINGULA ANATINA. 7 



blood corpuscles, whose decomposition soon takes place making 

 the fluid unfit for the development of eggs. 



Free-swimming larvae provided with 3-10 pairs of cirri were 

 captured by means of a tow-net drawn at, or a few feet below, 

 the surface. 



The stalked young of Lingula were secured by keeping 

 larvae with 8-9 pairs of cirri in a vessel in which the water 

 was changed every two or three days. I afterward searched for 

 the stages a little more advanced than those I was able to rear 

 from the free-swimming larva?, by examining in various ways the 

 mud from the flats where Lingula flourishes, but all in vain. 1 



From the beginning of fertilization up to the end of the 

 blastula stage all material was fixed with Flemming's fluid 

 (weaker formula), and vom Rath's ' picro-platin-acetic mixture; 

 these yielded fairly satisfactory results. For the later stages 

 several fluids were used ; among them saturated solution of sub- 

 limate in distilled water with the addition of a little acetic acid, 

 and vom Rath's picro-sublimate-acetic mixture proved best. 



All the embryos and larvae were cut in 5 n, and stained on 

 slides, except some of the older larvae, which were stained in loto. 



Of the stains used, Heidenhain 's iron-haematoxylin with 

 orange G or Bordeaux red proved best for the eggs. As for 

 embryos, borax carmine or carmalum followed by picric acid or 

 orange G gave the most satisfactory results. Haemalum with 

 counter-stain of erythrosin was also extensively used, especially 

 when it was desired to differentiate muscles from other tissues. 



1. Brooks, it may be recalled, was successful in securing the young of Glotiidia at this 

 stage by an examination of the mud of their habitat, but he has unfortunately omitted to 

 describe his mode of procedure. 



