78 JVilliam B. Herms 



Chemotaxis 



Two experiments were tried with reference to chemotaxis. 



First Experiment — Thirty-six larvae between four and five hours 

 old, were placed in a small vial 4.3 cm. in length, and a piece of 

 fish weighing about one gram was placed 1.5 cm. from the bottom 

 of another vial 12.7 cm. in length. While this was being done, 

 care w^as taken that the flesh did not come in contact with the 

 sides of the long vial. After the larvae were shaken to the bottom 

 of the smaller vial, the two were put mouth to mouth horizontally 

 on a table. This took place at 9.05 o'clock, a.m., June 30, 1905. 

 In three or lour minutes there was a decided movement toward 

 the mouth, but because of the unevenness of this region, the move- 

 ments became scattered. At this juncture a short piece of paper 

 was placed like a bridge inside the vials connecting them. 



The following table shows the results of the experiment. Un- 

 fortunately the data taken were not sufficient to make a complete 

 table. 



Second Experiment^A small piece of fish weighing about two 

 grams was placed in the center of a large sheet of heavy white 

 paper, then young larvae were put at diflFerent distances from the 

 flesh, after dipping them partly (posteriors) in glycerine so that a 

 trail would be left in crawling. 



The first larva was placed with head toward the meat at 9 cm. 

 distance, and reached the food in four minutes after taking a some- 

 what w^inding course. The wind was favorable in this case. 



A second larva was placed at a distance of 11 cm. with its head 

 away from the flesh and the wind at right angles. This larva 

 started at 10.32 o'clock, a. m. and after a very circuitous route, 

 circling frequently though always drawing nearer and never going 

 beyond, reached the food at 10.52 o'clock. Time, twenty minutes. 

 The course of this larva took it considerably to one side of the flesh 

 almost to the starting place of the first larva from which point the 

 two paths to the food were almost parallel. 



A third larva was placed at a distance of 11 cm. on the wind- 

 ward side of the food. After a great deal of traveling, making 

 many circles and stopping frequently like the other two, it reached 



