104 THE AMERICAN MONTHLY [Apr., 



pressed into pits which are lined with the striated-bor- 

 dered cells; on the areas between the pits are the ciliated 

 cells, and scattered irregularly among them all are the 

 granular club-shaped cells. 



An experiment was tried with milk similar to the one 

 tried on the larvae with practically similar results. On 

 treatment with osmic acid blackened granules were 

 found in the striated-bordered cells and underlying 

 tissues. 



It is evident from the above descriptions that pro- 

 found changes take place during the transformation 

 from the larva to the adult. A good series of larvae 

 was studied with the following results : The esophagus 

 of the adult develops very early in transformation. The 

 first stage in the clianges of the alimentary tract seems 

 to be a loss of definite structure followed by a rapid cell 

 increase and enlargement of the size and length of the 

 intestine. The gall bladder and ducts disappear and 

 the liver loses its simple tubular structure. 



Externally the mouth has gained its sucker-disc and 

 the skin is sheeny and gray. It was found that the 

 time required for these changes is probably not less than 

 seven or eight months, from August to March at the end 

 of which time the animal is ready for its parasitic life. 



During spawning season the last changes known to 

 take place in the life of the animal occur. In some res- 

 pects these are the most striking of the series of modi- 

 fications to which the digestive tract is subjected. At a 

 date estimated to be from two to three weeks previous 

 to egg-laying a sudden increase in the size of the gonads 

 of both sexes takes place. This is accompanied by an 

 equally sudden and rapid decrease in the size of the in- 

 testine. The liver changes to dark green. By the time 

 the sexual products are mature the intestine is reduced 

 from a tube of 1 to 1^ centimeters in diameter to one of 

 2 to 3 millimeters. 



