THE ADHESIVE ORGANS OF AMIA. 141 



Dean ('96) was the first author to treat of the development of 

 the adhesive organs in Anna. His description begins with an 

 embryo 138 hours after fertilization, that is, about two days 

 before hatching. At this time the organ is already well defined ; 

 he notes its paired character and states that at hatching it is rela- 

 tively at its largest size. Most of his observations have reference 

 to its degeneration and disappearance. This process begins in 

 a few days after hatching. By the seventh day the organ " is 

 reduced to a mere tubercle and is no longer functional." On the 

 tenth day " it is greatly reduced, although it does not in fact dis- 

 appear entirely (histologically) for several weeks. . . . Its atrophy 

 takes place first proximally, later marginally ; the cells of its 

 deepest tissues become greatly vacuolated and form a sponge-like 

 mass and the cell wall which here forms its anterior boundary 

 gradually encroaches ; the cells of the centro-distal region are 

 the last to retain their early character." 



In his general discussion of his observations he homologizes 

 the adhesive organs with " the typical pit organs, or sense buds 

 which later occur on other integumental regions " and uses this 

 homology as " evidence of how precociously embryonic and 

 larval structures may be developed." Needless to say we find 

 no basis for any such homology and no grounds for mentioning 

 the subject of precocity. 



In 1899 Miss Jessie Phelps working in Reighard's laboratory 

 published a brief article on the " Development of the Adhesive 

 Organs of Amia." This writer says : " The organ is formed in 

 a very early stage as a diverticulum of the foregut. This diver- 

 ticulum subsequently divides into two, each of which continues 

 to communicate for a time with the cavity of the foregut. Each 

 of the two diverticula later separates from the foregut, becomes 

 elongated and curved into the form of a semicircle and divides 

 into from six to eight closed vesicles. The vesicles finally open 

 to the exterior and are thus converted into cups. After being 

 functionally active for a time the organ is pushed beneath the 

 surface by the thickening ectoderm, becomes infiltrated with 

 leucocytes and finally disappears (larvae of 20-25 rnm.) without 

 leaving any trace behind it." 



The results of our work confirm the findings of Miss Phelps as 



