FISH PARASITES COLLECTED AT WOODS HOLE. 
301 
On the Occurrence of Cysts in the Stomach Wall of Pomatomus saltatrix. 
[Plate 42, fig. 101, TJ. S.N.M. No. 0529.] 
A piece of the stomach wall, about 8 mm. square, comprising the mucosa and submucosa taken 
from tlio stomach of a blue-fish July 23, was stained in borax carmine and sectioned. 
One of these sections, measuring 8 mm. in length, bad passed through six distinct cysts, each 
containing, so far as it was possible to determine, a larval Tetrarliynchus. Some of the cysts contained 
embryos which were too young for certain identification. The combined length of these cysts was 
3.5 mm. The superficial area included in the sections of these cysts represented two-fifths of the 
area of the submucosa of the entire section. If this ratio of cysts and submucosa were maintained 
throughout the stomach of the fish it would follow that something like 12 per cent of the tissue of the 
stomach consists of foreign tissuo if not actively inimical to life at least passively so. The amount of 
energy consumed in building up tho protective cysts about these embryos, and of digested and absorbed 
food which is diverted to the use of these vagrants, must bo considerable. Tho above is possibly some- 
what above the average, although it may bo below it, for it is a common thing to find the submucosa of 
the stomachs of blue-fish, squeteague, flounders, etc., so full of cysts that the space occupied by the cysts, 
as seen on superficial view, appears to be quite as much as the space remaining between the cysts. 
The outside wall of each cyst consists of connective tissuo fibers in concentric circles, compact 
but merging in places into the connective tissue elements, with numerous nuclei. Within this is 
the cyst proper, tho outer layer of which stains deeply in carmine and is made up of a few concentric, 
plate-like, structureless layers, which are somewhat brittle. Within this is tlio blastocyst. The outer 
layer of blastocyst and the closely underlying muscular elements stain moderately, but tho inclosed 
parenchyma, which makes up tho interior, stains very little. The embryo, on the other hand, stains 
quickly and strongly in carmine. The parenchyma in those sections is an opened meshwork of unstained 
tissue, with sparse nuclei scattered through it. Near the boundary the nuclei become abundant. 
Tho above-mentioned membranes were measured in one cyst with the following result, dimensions 
in millimeters: Thickness of outer nucleated connective layer 0.02, of inner non-nucleated layer 
0.007, of outer layer of blastocyst 0.007. 
Cysts from Kidneys of Soup. 
[U.S.N.M. No. 6530.] 
Small globular cysts were found in tho kidneys of a scup ( Stenotomus chnjsops) August -1. These 
cysts were about 1.5 mm. in diameter. Two of them were opened, but nothing could be made out of 
tho contents. There wore also small blotches of black pigment on the surface of the kidneys. 
A few of these cysts were sectioned, with the following result : The cysts appear to be small 
tumors, 1 mm. or less in diameter. They are composed entirely of connective tissue and are exceed- 
ingly compact. Toward the periphery of tho tumor there is a concentric arrangement of the fibers 
which is quite distinct, portions showing a tendency to separate, or rather to become slightly loosened 
from the general mass. Though this concentric arrangement was traceable from the greater part of the 
periphery well toward the center, it was lost near the center, and at one sido was indistinct. Nuclei 
were abundant throughout the mass. Only the tumors, with what tissues remained adherent to them on 
removal from kidneys, were preserved; but tho sections disclose an abnormal condition of tho adjacent 
tissues in that they are infiltrated with blood so as to resemble a blood clot with a few uriniferous 
tubules penetrating it. In this infiltrated tissue lie also numerous small black pigment masses. 
Such conditions call for further investigation to bring out the actual structure and the extent to 
which the tissues are affected. No nucleus could bo distinguished in any of the tumors sectioned. 
On Cysts in Stomach-wall of the Black Sea-bass ( Centropristes striatus). 
[Plate 42, ligs. 103, 104, U. S. N.M. No. 6531.] 
A number of sections were made and mounted serially of a part of the stomach- wall of a black 
sea-bass, collected July 28. A study of these sections reveals the fact that some of these cysts are 
formed around blastocysts which contain larva;. In a few cases they were developed far enough to 
show by the character of tho hooks that they were near if not identical with forms already described 
from this host. (Notes on Larval Cestode Parasites of Fishes, pp. 793-794, pi. n, fig. 12.) Others are 
too young to admit of identification further than that they represent the early stage of some cestode 
worm, but presumably most if not all of them belong to tho genus Rhynchobothrium , and possibly 
to a single species. 
