THE MYXOSrORIDIA, OR PSOROSPERMS OF FISHES. l77 



Tubes rather frequent in very many fresh-water copepods, the affected 

 [Page 15] individuals beiuj;- distinguishable at first glance from the healthy by their 

 opacity, the places where the parasites lie appearing dark. If in great 

 number, the Cyclopn appear completely opaque, and, indeed, according to 

 [Page 16] Schmell (loc. cit., ]». 20), may appear dark brown to black. Discoloration 

 caused by larger or smaller tubes (illed with pyriforni, sporo-like cor- 

 puscles; tubes occurring in body-cavity, ami variou.s other places, as the thorax, 

 abdomen, tail, natatory feet, ar.d first antennre; sometimes in so great numbers that 

 no part of the body is free from them. Spores iu some places not in tubes but free 

 in body-cavity, then always found directly on the muscles. 



These parasites were probably those which Claus ol)serve(l in copepods and 

 regarded as spores of fungi; also extremely probably those noted by other observ- 

 ers, in various crustacea, e. g., Henueguy in Palmnon rectirostris and P. serratn-^, 

 Henr.ej^uy and Thelohan in Crangon vulgaris and Jslactts fluviatilis, and Garbini in 

 PaIn>monetes varians. However, it can not with certainty be asserted that the 

 parasites found in the last-mentioned crustaceans are identical with the Cyclops 

 parasite, as to the short communications no figures ' are added, and the authors iu 

 question were unable to follow the whole developmental history. 



Technique. — The allected Cyclops was isolated in a drop of water on the 

 [Page 17] slide and covered with a cover glass provided with wax feet, fixed in posi- 

 tion by careful pressure on the angles of the cover-glass, so that it 

 remains quiet and can be conveniently observed even with a high power (apochr. 

 4 mm.). Between the observations the Cyclops was at first kept in a hanging drop 

 in the moist chamber, but lived only a few (2-3) days, dying partly from starvation, 

 partly from other unfavorable conditions. Consequently the Cyclops was next 

 kept in a watch-glass of water, thus securing necessary food supply. Thus kept, 

 it lived 14 days, allowing the development of the parasites to be followed. 

 Several individuals were kept simultaneously and examined 2 to 4 times a day. 

 Investigation of dead or crushed specimens is not to be recommended, as great bacte- 

 rial development soon disturbs the study. For observation of the finer anatomical 

 features and the developmental stages, the parasites were isolated by crushing tlie 

 host and observed Avith very high powers (liomog. immers. apochr. 2 mm., oc. 12 

 and 18). For fixation, picro-sulphuric, andchromo-aceto-osmic acids; for stains, alum 

 carmine, ha^matoxylin; also methyl violet, safranin, and fuchsin. I'^xaminations 

 were made partly in water, ]tartly in glycerin. 



1. Amocbiform stage. — Met with in all parts of the body; most easily 

 [Page 18] observed on the first antennae. Form amcoboid-variable, globular or 

 elongate; dimensions varying from 7/i long by 3// broad, to 20ju long by 

 6/i broad. Plasma finely granular, cai)able of emitting on all sides blunt, lobulato, 

 hyaline pseiidopodia, always possessing a nucleus (pi. 4, fig. 2 N) and a small con- 

 tractile vacuole (c. v.). Nucleus globular, showing the familiar vesicular structure, 

 that is, in its interior, a globular, homogeneous, more strongly refriugent and more 

 deeply staining nucleolus [^Binnenkorpcrl. Contractile vacuole constantly situated 

 near the border, in the end of the body which during progression is hindermost, pul- 

 sating about once every 30 seconds; no food vacuole perceptible. 



This amoiba ordinarily creeps about over the epithelial and muscle cells and prob- 

 ably feeds upon the same, as, although not directly observed, many epithelial cells 

 were seen destroyed, and upon tliom anncbie. 



After attaining a certain si/o the amcubfe gradually cease their movements, draw 

 in their pseudopodia, and encyst themselves. 



The amreba' may fuse to large plasmodes; several such fusions of 2 or 3 auKcbae 

 (pi. 4, fig. 8) were directly observed. Size of plasmodcs varying with size and 



'The author is partly iu error as regards the absence of figures. They will be 

 found in the papers of Henueguy and Garbiui. 

 P 12 



