266 



SCIENCE. 



[N. S. Vol. XXI. No. 529. 



erable part of the body is covered, then 

 there is a siiake-like movement in the sand 

 and the animal quickly draws itself com- 

 pletely under. With the Ammocoetes the 

 process of entering the sand is performed 

 slowly enough to enable one to see all the 

 steps. AVith Amphioxus and Asymmetron 

 the movement is so rapid in vigorous indi- 

 viduals that one can not see the details. 

 They seem to enter the sand like an arrow. 

 When the animal becomes weakened from 

 any cause or weary by much swimming and 

 entering the sand, the movements become 

 sufficiently slow to enable one to follow the 

 steps. 



4. Ammocostcs always enters the sand 

 head first. Ampliioxus usually goes head 

 first, but may enter the sand tail first. 



5. Both forms feed continuously, the 

 food being derived from the respiratory 

 stream entering the common branchio- 

 esophageal chamber. In Amphioxus the 

 respiratory stream is produced by ciliary 

 action. In Ammocaites the stream is pro- 

 duced mostly by muscular action on the 

 two folds of the velum. 



6. From the manner of feeding in nature 

 it is easy to carry on feeding experiments. 

 Any food, if finely enough divided to pass 

 the sieve guarding the hood or oral en- 

 trance, will find its way into the digestive 

 tube. 



7. While both these forms live normally 

 under the sand, each has a free life— the 

 Amphioxus in its beginning or larval stage, 

 and Ammocaites in its adult or terminal 

 stage. 



8. Method of Cr/pfxre.— With Amphioxus 

 in Bermuda the animals live most abun- 

 dantly in places where there is a current. 

 The depth of the water is not, apparently, 

 of great importance, as they were obtained 

 in depths of a few inches up to a depth of 

 thirty to sixty feet. It is only necessary 

 to scrape up some of the sand with a dredge 

 or dipper and look over the sand. When 



exposed to the air the animals wriggle 

 vigorously and then are easily seen. If 

 they remain quiet, they are seen with diffi- 

 culty, they look so much like the sand. 

 Ammocoetes is taken in the same way. It 

 usually lives on the edge of a stream and 

 it is easy to shovel up the sand and mud 

 and look it over. The wriggling movement 

 helps here also, as the coloration of the 

 animal and that of the sand are almost 

 identical. 



9. Hardiness of the Two Forms.— Both 

 are very hardy, and hence it is easy to keep 

 them in the laboratory. Food will be sup- 

 plied by the water, or one may feed them 

 any desired food, as cooked flour, finely 

 divided yolk of hard boiled egg, etc. 



10. It was found possible to keep Ammo- 

 coetes in the laboratory from four to six 

 months without doing more than change 

 the water occasionally. Amphioxus and 

 Asymmetron w'ere captured the middle of 

 August in Bermuda, taken to Ithaca in 

 fruit jars of sand and sea water, and in 

 this way some of them lived until the first 

 of December. This experiment shows, I 

 think, that it is entirely practicable to have 

 living Amphioxus for study and experi- 

 ment in our northern and inland labora- 

 tories. 



Vitality of Mosquito Eggs: John B. Smith, 

 Rutgers College. 



The salt marsh mosquito, Culex sollici- 

 tans, lays its eggs in the soft mud on salt 

 meadows and these eggs may remain for 

 months, losing nothing of their vitality. 

 After lying dry for a long time a large 

 percentage hatches within a few hours after 

 becoming covered with w^ater. The re- 

 mainder lie dormant for a period long 

 enough to enable the first lot to reach full 

 growth and then, if they are yet water cov- 

 ered, most of them hatch. A few eggs of 

 each brood lie over until the year follow- 

 ing, and all the eggs of the last brood 

 hibernate. The first spring brood of these 



