334 Mr. Goodsir on the Conferva which 



these edges were observed to be shrivelled, not, as appeared to 

 me, by a process of ulceration, but by an irregular interstitial 

 absorption. This absorption was more evident along the 

 bounding edge of the parasitic mass, where it presented the 

 appearance of a furrow, in which the parasite grew with more 

 luxuriance than elsew'here. 



What was the exact state of the surface to v>hich the para- 

 site adhered I am not prepared to say. I could detect no sub- 

 stance corresponding to the false membrane described by cer- 

 tain observers as constituting the soil on which vegetate 

 those parasites which infest the air-cells of birds : neither 

 could I satisfy myself that the substance which formed the 

 infested surface was merely the mucous covering of the fish. 

 I am inclined however to lean to the latter opinion, for two 

 reasons ; first, because the surface exhibited the pigm.ent cells 

 of the skin ; and secondly, because I detected solitary indivi- 

 duals attached to the broad scales of the back. 



Each plant consists of a jointed filament, in some indivi- 

 duals single, in others dividing dichotomously towards the 

 attached extremity, but more frequently near the summit. 

 The filament tapers gradually from the base to the summit. 

 The former is very slightly dilated, rounded and closed at the 

 extremity, which is destitute of appendages. The latter va- 

 ries in different individuals under different circumstances, as 

 will be afterwards described. The articulations are elongated, 

 varying in length fi'om ten to fifty times their breadth. Basal 

 articulations w ere met with, having a breadth of the 800th of 

 an inch ; acute or barren teraiinal ai'ticulations were about the 

 2000th of an inch. The length of the articulations increased 

 towards the summit, the basal being in general the shortest. 

 Each articulation w as tubular, filled with a transparent fluid 

 in which floated granules. Their walls appeared to be homo- 

 geneous, I could detect no double membrane ; but at the spot 

 where the neighbouring articulations were connected, the in- 

 ternal surface of each appeared to leave the external surface 

 of the filament so as to form by conjunction the flat dia- 

 phragms. It would appear, then, that the walls of the cells 

 are originally double, but have coalesced in the progress of 

 growth. Towards the basal extremity of each articulation, 

 generally close upon it, but sometimes a little removed, is a 

 globular transparent vesicle. This vesicle varied in size, di- 

 rectly as the diameter of the articulation. I did not observe 

 this vesicle in any instance exhibiting a nucleus or granular 

 contents. I occasionally observed it floating free in the fluid 

 of the articulation ; but this might have been the effect of vio- 

 lence. The fluid of certain of the articulations contained arra- 



