70 
agreement 1s Lymphosporidium trutte, the cause of a 
brook-trout epidemic in America. In most respects this 
parasite, described by Calkins (1), is very different from 
Lymphocystis, the adults bemg amoeboid, relatively 
minute, and with no well-defined nueleus--the chromatin 
oe 
being in the “ distributed ” form, The two parasites are, 
however, not without certain points of resemblance. 
Lymphosporidium is, especially in the adult sporulating 
stage, chiefly met with in the lymph-spaces surrounding 
the various organs and of the dermis. Moreover, its 
manner of reproduction rather recalls that of Lympho- 
cystis. .Aecording to Calkins, deeply-staining granules 
collect 1m masses to form many spores. The chro- 
matin next forms a layer around the periphery of each 
such centre, and breaks up into rounded granules, eight 
in number, which separate (¥) to form the sporozoites. 
From Calkin’s figures, it does not seem to me unlikely 
that the complicated reticular areas in Lymphocystis (2.e. 
the threads of rodlets or granules above described) may 
represent a modification of this process, although at 
present one cannot say so with certainty. In that case 
the ultimate germs must be extremely minute (only 
about | or 13 uw) and numerous. Whether the little 
spherules at the margin of the endoplasm have any con- 
nection with spore-formation and are in any way com- 
parable to the reproductive organelle or ** pansporo- 
blasts ” of Myxosporidia has also yet to be ascertained. 
In conclusion, Lymphocystis would appear to com- 
bine, to a certain extent, Gregarine and Microsporidiam 
characters—with remarkable results. I do not feel 
inclined to place it in the Serosporidia (the order to which 
Lymphosporidium belongs), as these forms, though of 
similar habitat, are all very small. I have, unfortu- 
nately no alternative but to leave it for the present, to 
swell the ranks of the * unattached ” Sporozoa. 
