1204 BULLETIN OF THE BUREAU OF FISHERIES. 



1. As to the fact that these parasites have the habit of gaining lodgment 

 in the fiesh of the butteriish, it may be said that evidently here is a case of 

 mutually favoring conditions. A careful study of the anatomy of the butterfish, 

 especially of the vasctdar system, may throw some light on the problem. At 

 any rate the fact that the larvae of Otobothrium crenacollc penetrate to the muscles 

 of the butterfish and harvestfish, instead of lodging in the submucous coat of the 

 stomach and intestine, as is their habit in other fishes in which this cestode has 

 been found, is probably a purely physiological question. The other species of 

 Otobothrium mentioned above presents a somewhat similar case. In the case of 

 the gars, however, a large number of small gars have been examined for flesh 

 parasites without any being found. Either the infected gars were exceptional 

 cases, or it is only in certain regions that the conditions favor the ingestion of 

 cestode eggs. 



It would appear that certain species of the Tetrarhynchidae, and notably of 

 the genus Otobothrium, are enabled to penetrate to the muscles of certain inter- 

 mediate hosts, possibly on account of being of suitable size and structure so that 

 they are carried by the blood away from the immediate vicinity of the viscera. 

 Or, more probably, there is here a case of accidentally mutual adjustment on the 

 part of the anatomical structure, and possibly the physiological habit of the 

 butterfish on the one part, to the structural features, and possibly the physi- 

 ological requirements of the parasite on the other. 



2. That these cysts should be present in very large numbers in a single fish 

 is not difficult to understand once given the possibility of their being in the flesh 

 at all. A free, ripe segment of the cestode Otobothrium crenacolle will remain 

 living for hours after it has been placed in sea water. Moreover, it may contain 

 an enormous number of eggs. There is no necessity, therefore, in postulating 

 some method of reproduction of cysts by budding, for which there is not the 

 slightest evidence, to account for the presence of a large number of cysts in a 

 single butterfish. The ingestion of a single joint, in which there is a large num- 

 ber of eggs, will be sufficient to give rise to several hundred, possibly a few 

 thousands of cysts, each with its living scolex. Indeed it is rather easier to 

 explain the cases in which there are hundreds of cysts than it is to explain those 

 in which there are less than a dozen. Cases of slight infection are probably due 

 to the accidental swallowing of a few eggs instead of an entire joint. This might 

 happen if a fish swallowed a bit of fecal matter which might well have one or 

 more eggs intermingled with it. 



3. How is the apparently almost universal parasitism of the butterfish to 

 be explained? Before attempting to answer this question it may be well to 

 consider whether the case, aside from the fact that the cysts are in the muscles, 

 is unique. Unfortunately, I have not my notes arranged in such a way as 



