284 DR BENNETT UPON PARASITIC VEGETABLE STRUCTURES 



III. 



On the Structure of a Cryptogamous Plant found growing on the Skin of the Gold-Fish, 



(Cyprinus auratus.) 



For such notices as have already been published connected with the growth 

 of vegetations on living fishes, I must refer to a subsequent part of this memoir. 

 As in no case, however, are details entered into, I am ignorant whether the vege- 

 tations or confervse alluded to are the same as those which I have myself perso- 

 nally examined. 



Mr GOODSIR was the first who examined microscopically the vegetations found 

 growing on the gold-fish. The fish he examined was observed to be in a lan- 

 guishing state for some time before death, and to be covered with a white efflo- 

 rescence, of considerable length, which sprung principally from the dorsal fins and 

 tail, and floated in the water. The animal was dead before being put into his pos- 

 session. Some days afterwards, he kindly placed at my disposal some of these 

 filaments, which I examined microscopically, and the following are the results. 



Viewed with a power of 300 diameters, two very distinct structures were ob- 

 served. One of these might be called Cellular, the other Non-cellular. 



The cellular structure was composed of elongated cells, which varied in thick- 

 ness ijjo to ^ of a millimetre, presenting the appearance of long jointed tubes, 

 which often extended twice across the field of the microscope. They were fre- 

 quently branched, generally in a dichotomous manner, although sometimes three 

 branches were given off from one joint. Some of the cells were empty, and ap- 

 peared very transparent ; others were full of granules, which varied in size from 

 55 to ilo f a millimetre in diameter. Every possible degree of variation ex- 

 isted in the quantity of the cellular contents, some being full of granules and 

 opaque, others being partially so, and others again empty and very transparent. 

 In most of the cells, a distinct nucleus existed, which appeared as a transparent 

 vesicle about ^ of a millimetre in diameter. Some contained two nuclei. 

 (Plate VII. fig. 10.) The nuclei were generally (not always) placed at the'proxi- 

 mal end of the cell, from which came off sometimes two other cells, more rarely 

 three, giving a branched appearance to these vegetations. (Fig. 12.) On applying 

 pressure, and by means of a little manipulation, the granular matter Avithin any 

 particular cell could readily be made to flow from one end to the other, or forced 

 out by rupturing its walls. These jointed cellular tubes Avere often grouped to- 

 gether, forming a mesh-work, in which the cells filled with granules ; and those 

 Avhich were empty could readily be distinguished from each other by their opaque 

 and transparent appearance. (Plate VII. fig. 8.) 



As regards the substance from which this jointed structure arose, it appeared 

 to be an amorphous mass, composed of very minute granules almost identical with 

 the matter found in the capsules of the Porrigo, and tubercular cavities formerly 

 described. It appeared very abundant below the scales from Avhence the tubes 



