MORPHOLOGY OF MELIBE 571 



formed of robust folds and studded with glands which are 

 the glands of the n i d a m e n t o ; near the opening of the 

 oviduct into the vagina but still more dorsad opens the gland 

 of the albume. This is contrary to that noted in other 

 tectobranchs in which the albume gland terminates in a 

 vast number of minute ductuli with blind origins arranged in 

 such a way as to constitute un fitto gomitolo. The 

 albume gland of Pleurobranchaea resembles much in 

 structure the albume gland of some nudibranchs, e. g. E r c o - 

 lania (? Hercolania) as described by Trinchese. 



The albuminous gland of M. leonina seems to be more 

 uniform in its physiological condition relative to that of the 

 mucous gland. Unfortunately, I have not at the present time 

 worked out its exact relation to the oviduct, but in general it is 

 somewhat like that described by Mazzarelli for Oscanius 

 and Ac era, i.e. the nidamental gland is nearer the orifice 

 of the vagina than is the albuminous gland. The epithelium 

 of the nidamental gland which secretes a great deal of mucus 

 at the time of oviposition shows some very interesting things 

 relative to its activity during such a time (PI. 37, fig. 84, A-C) : 



1. The nucleus (B) presents no visible membrane, the nucleo- 

 plasm being filled wdth almost uniformly sized granules which 

 seem to be formed by the nucleolus and then pass as a liquid 

 into the cytoplasm of the cell where from small, minute 

 micromeres the cell becomes entirely filled with darkly staining 

 macromeres which seem to have grown from these smaller 

 ones so that the ordinary and less stainable cytoplasm is 

 practically obliterated, i.e. obscured by these granules. 

 These granules are very strongly basophil in their staining 

 reaction. The macromeres then liquefy and pass out of the cell 

 and into the lumen of the gland. 



2. This leaves the cell in a condition strongly contrasting 

 to the one before the liquefying of the mucus. The cell is now 

 very vacuolated, containing a non-stainable, or rather oxyphil, 

 substance {A, Bs) with relatively few granules. These granules 

 are micromeric, and are aggregated in the meshes of the reticular 

 net-work of the cytoplasm. 



