our observations the eggs of this species, numbering about 75 to 125, form a 

 packet of very long filaments by means of ent'wining, which (the packet, 

 nobis) is deposited all at once and does not delay itself on the gills of the 

 host but falls into the water. In the water it turns upside down with the 

 spool of the filaments down; the eggs comprising it spread fanwise in all 

 directions forming a shape similar to that of a little umbrella or parachute 

 which settles very slowly. The little feet of the eggs point in all directions 

 with their hook-shaped ends and grab the sea plants and prevent the whole 

 group of eggs from settling out of the water. This contrivance undoubtedly 

 is consistent with the conditions of life of the Terpug, Hexagramidae--the 

 host of M. gotoi--so that the emerging larvae will fall into more or less 

 favorable conditions for the infection of the young host (for more details 

 see page 118). As a rule the eggs of the representatives of the second 

 group have more or less well-developed little feet and very often filaments. 

 Often the eggs attach themselves to the body of the host by the little feet, 

 and it is quite probable that they attach themselves not only mechanically 

 by the terminal widening but also glue themselves to it. Usually during this 

 process the maternal individual performs special motions while depositing 

 the eggs which help in the gluing of each egg individually. Thus, the eggs 

 of Nitzschia sturionis (Abildgaard), according to our observations, glue 

 themselves to the mucous membrane of the buccal cavity of sturgeon-type 

 fishes. Even in artificial conditions in a glass container the eggs glue them- 

 selves so strongly that they cannot be torn away by a strong stream of w^ater 

 fronn a pipette. Among species with sharpened feet and filaments, the latter 

 retard themselves on the body of the host by mechanical action. For in- 

 stance, according to our observations of Mazocraes of Caspian herring, 

 during the period of intense egg-laying on the gills of the host there are many 

 hundreds of deposited eggs and they are attached to the gills very strongly 

 in spite of the fact that they do not have any special growths or indentations 

 on the little feet or on the filaments. It is quite probable that the gluing of 

 certain Hexabothriidae in long chains of from 10 to 15 units each, which 

 was observed by Thaer (Thaer, 1850), appears as an adaptation to the 

 easier retention of the eggs on the body of the host. There is reason to 

 believe that the eggs of all monogenetic trematodes have an envelope which 

 is agglutinous to some extent. Study under artificial conditions, however, 

 does not permit us to substantiate this with complete conviction. 



Embryological development of the egg -laying species has been in- 

 sufficiently studied. For all practical purposes only the development of 

 Polystoma integerrimum Froelich was studied (Goldschmidt 1902a, 1902b; 

 Halkin, 1901). ^ In this species the cleavage is complete and unequal and 



•'• P. G. Svetlov pointed out to us the existence of one more work (Minouchi, 

 1936) which was not known to us at the time of the writing of the present 

 section. 



91 





