I080 BULLETIN OF THE BUREAU OF FISHERIES. 



papers previously referred to (1891, 1899, and 1899a), also refutes this error. 



In her first paper (1891) she says: 



The adhesive disk ■" * * is about 3 millimeters in diameter. It is a trans- 

 parent thickening on one pole of the egg membrane, at the time of oviposition, and by 

 means of it the egg is glued firmly to the rock. 



Later she writes more explicitly (1899): 



The young fish do not attach themselves by a ventral disk which soon disappears, 

 as has been supposed, but at the time of oviposition each egg is securely glued to the 

 rock by means of a secretion on the membrane at the pole of the egg opposite the micro- 

 pyle. After hatching, the embryo fishes still remain attached to the rock by the adhe- 

 sion of the yolk sac to the inside of the egg membrane over the disk area until the yolk 

 material has been entirely absorbed, a period of three or four weeks. 



Again, she says (Clapp, 1899a): 



The membrane of the egg has a peculiar adhesive disk, about 3 millimeters in diam- 

 eter, which has a constant position, with the center of the disk at the vegetative pole, 

 directly (?) opposite the micropylc. By means of this disk the egg is firmly glued to 

 the supporting surface. * * * The disk consists of a transparent secretion, which 

 becomes opaque and gluey on contact with water. It is of nearly uniform thickness, 

 and is closely applied to the egg membrane everywhere, except for a narrow margin 

 which projects all around as a thin rim. The disk is saucer shaped and only a little 

 thicker than the egg membrane itself. I have been able to separate it from the mem- 

 brane in the case of eggs hardened before attachment. As the egg is generally fastened 

 to more or less plane surfaces, it appears strongly flattened on the side of attachment, as 

 described by Doctor Ryder and as shown in figure 3. 



This is correct, and Miss Clapp has been quoted at some length in order to 

 give her the credit for discovering the disk and for refuting the errors above 

 noted, and because her clear statement of the facts could not be improved on 



by me. I am pleased 

 to say, however, that on 

 June 22, 1908, I ascer- 

 tained that the adhesive 

 disk is to be found in 

 place opposite the micro- 

 pyle in ripe ovarian eggs 

 when these are allowed to 

 flow from the ovary into 

 water, thus confirming 

 Miss Clanp's statement 



Diagram 'after Miss Clapp) showing adhesive disk of toadfish egg. A.hefoie, (1891) that the disk is 

 B, after attaehment. (Much enlarged.) prCSCnt at the time Of 



oviposition. When the egg becomes fixed to some supporting body both 

 the disk and the egg become very much flattened on the supporting side. The 

 accompanying text figure " shows both these points clearly. A is a ripe egg 



oCopied from Miss Clapp (1899a). This is the "figure 3 " referred to in the quotation above. 



B 



