1 64 THE AMPH10XUS. 



becomes more marked. The anterior end of the body, 

 which grows out triangularly, and the caudal fin 

 continue their formation. 



The embryos, which are covered with long flagella, 

 move only exceptionally by a lateral twisting of 

 the body. Whereas the flagellated embryos, however, 

 continued hitherto on the upper surface of the water, 

 they now begin to sink some distance down. In the 

 glasses they sink to the bottom. 



With regard to the flagellation of the body, we must 

 mention a phenomenon already noticed by Ko.walev- 

 sky. He describes it as two tactile threads, which are 

 formed on two little warts on the lower side not far 

 from the mouth. " Treatment with acetic acid," he 

 says, " will show that these tactile hairs consist of two 

 long cilia which have coalesced." 



I myself found the same, consisting of a number of 

 separated, somewhat strong and motile cilia, which 

 are situated upon a small wart-like projecting thick- 

 ening of the epiblast, a collection, that is to say, 

 of small columnar epiblast cells. This thickening 

 of the epiblast is on the left side of the body, 

 immediately in front of the anterior edge of the 

 mouth, and its cilia incline towards the mouth. 



