1130 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [4] 



the body, and that he had never succeeded in making these infusoria 

 absorb carmine. Fouquet therefore supposes that this nppareut opening 

 is an apparatus used by the infusoria for adhering to other objects, and 

 that food is absorbed only by an endosmotic process, as in Ophalina. 

 So far, however, it has remained utterly incomprehensible to me how a 

 parasite living between the epidermis cells of a fish, which has therefore 

 no immediate accesa to liquid food, could absorb food by an endosmotic 

 process. 



After Fouquet has mentioned the horseshoe- shaped nucleus, he gives 

 a full description of the mode of reproduction of these infusoria. The 

 fully developed individuals go through a process of encystation, and 

 ultimately of fission, which, after three or four days, results in the 

 production of numerous small infusoria (0.04(5 millimeter long and 0.028 

 millimeter broad). The sarcode of these young infusoria is not of a 

 granular character, and they possess no sucking-disk. Whether instead 

 of this apparatus these young individuals have a mouth opening, or 

 what changes the anterior pole of the body undergoes during its further 

 development — in what way, that is, the sucking disk develops in the 

 grown animals — all these are important questions which j^resent them- 

 selves to the reader of Fouquet's treatise, but which he leaves entirely 

 unanswered. 



Fouquet states, in conclusion, that in the fish-cultural tanks of the 

 College of France this infusorial disease alfects the young trout only 

 during three months of the year, from the end of May till some time 

 in August. The youug trout became completely emaciated, tlie epider- 

 mis formed became thickened at certain points in whicli the infusoria 

 were gathered; finally, fungi began to form, and soon death came. 

 Fouquet thinks that a higher temperature of the water, and an increased 

 supply of the same, favor the development of the infusoria. When, 

 in 1876, the hatching troughs received their water from another source, 

 the disease, and with it the infusoria, disappeared. 



Fouquet finally discusses the question as to the place to be assigned 

 in the system to these infusoria. In view of their structure and shape, 

 manner of propagation, and anatomical differences between the young 

 and the grown individuals — all of which difler greatly from anything 

 observed in other infusoria — Fouquet assigns to this infusorian a special 

 place, and calls ItlchthyophtJiirkismtdtifUiis, grouping it with the hetero- 

 trichous infusoria. 



As a third communication relative to the occurrence of infusoria on 

 the skin of fishes, we must mention a statement made by Livingston 

 Stone,^ who, in the work referred to, takes great pains to describe 

 a parasite on the skin of Trutta forio L., which, in the spring of 1872, 

 made its appearance in his hatcheries in vast numbers. The description, 

 however, is so superficial, so vague in every respect, that I find it 



^Livingston Stone: "Domesticated Trout: How to breed and grow tliem." 3<i 

 edition. Charlestown,N. H., 1877, p. 277. (Appendix 1. A new discovery.) 



