to 15 iTieters and approach the shore only in spring. Spawning apparently 

 takes place in August and during that time the adult individuals approach 



1 



It is known precisely that near Hokkaido H. octogrammus spawns in the 

 second half of August; near Shikotan the individuals of H. lagocephalus 

 which had just spawned were encountered from the end of August. 



the shore very closely. After spawning, adults return to the greater depths. 

 The young fishes in ages up to two years basically nnaintain themselves in 

 shallow water the entire sumnner, almost right by the shore, and in late 

 fall migrate to greater depths. Juxtaposing the data on biology of fishes 

 with the parasitological data, we see that the life cycle of M. gotoi (Fig. 



125) is fully adapted to the peculiarities of the life cycle of the fishes. Also 

 the reasons for the absence of larval stages and developing worms on the 

 adult fishes until fall and also the absence of infection of young ages become 

 clear. At the same time, the data cited indicate that the life span of M. 

 gotoi individuals is not less than a year and most likely is even longer, be- 

 cause on adult two-year-olds we find worms of somewhat lesser size than 

 on the older fishes. 



The life cycle of Polystoma integerrimum Froelich is extremely 

 complex. Excellent observations of P. integerrimum Froelich, which para- 

 sitizes different frogs, mainly Rana temporaria Li.,were expressed in the 

 works of Zeller (Zeller, 1872a, 1876) and Gallien (Gallien, 1935). We also 

 have considerable material. It was obtained as result of three -year obser- p. 121 

 vations in 1927 to 1929 in the region of the Peterhof Institute of Natural 

 History. Because of the differences of geographical points of research be- 

 tween our material and the information of the above-mentioned authors, there 

 are a number of differences; mainly in the lengths of different processes. 

 Because of this, we shall outline the life cycle of ^. integerrimum in general 

 traits and then reproduce certain calendar (chronological, nobis) data based 

 on our and Gallien's observations. The examination of the life cycle (Fig. 



126) begins best with the winter period of the year and with fully adult indi- 

 viduals --4 to 5 years. At this time all the wornns have a fully developed sex 

 system completely ready to begin functioning but still inactive. The worms 

 are located in the urinary bladders of the hibernating frogs. In early spring 

 as the latter emerge from that portion of the body of water in which hiber- 

 nation took place, the sex system of P. integerrimam begins to function and 

 a few days later, during which the "excision" of egg cells (see page84 ) takes 

 place, egg deposition begins. Toward that time the frogs pair and again 

 depart into the water to a place where a day or two later they deposit roe. 

 The eggs of P. integerrinnunn are deposited in the same place and almost 



at the same time as the roe of the frogs. However, the deposition of the 

 roe terminates somewhat earlier than the deposition of the eggs of P. 

 integerrimum because the former usually takes place within 6 to 15 days 



126 



