THE MYXOSPORIDIA, OR PSOROSPERMS OF FISHES. 171 



However much (or little) tliis may i)rove as to tlie stability of body- 

 form in the Gregarines, I can not see that it proves anything as regards 

 the Myxosporidia. Further, I can not see any resemblance between the 

 spores of Lithocystis, which contains falciform germs and no capsules, 

 and the capsulate myxosporidian spores. 



Perrier includes it among the Myxosporidia. 



Finally, the following excellent paper (seen and incorporated at the 

 last moment) seems to settle the question beyond doubt, and serves to 

 remove almost the last " transition" form from the taxonomic doubtful 

 list: 



L. Cueuot: Commeusanx et parasites des ficliinodermes ; Rev. Biolog. Nord 

 Frauce, Lille, v, Oct. 1,1892; Lithocystis sclmeideri Giard, pp. 4-6, plate 

 1, tigs. 1, 2. 



The following is an abstract: 



L. schneideri is a perfectly typical monocystid Greaarine; the gregariue stage 

 probably occurs in the digestive tube, being rarely encountered in the body cavity, 

 the Gregarine probably encysting soon after traversing the intestinal walls. In fact, 

 cysts are encountered upon, but not attached to, the intestinal wall. In the body 

 cavity the Gregarine was always found (whether accidentally or otherwise) in the 

 midst of a mass of cysts. Gregarine ovoid, about 65 // long, protoplasm very vacuo- 

 late, inclosing a rather large number of clinorhorabic crystals, which also occur in 

 the cysts; a voluminous nucleus, with large nucleoli, is present. 



Masses of the spherical cysts, well described by Giard, occur of all dimensions (ad 

 max. 1 to 2 mm.) in ditferent regions of the body, especially on the intestine and on 

 the oral surface. They inclose a considerable number of spores and a voluminous 

 rest of segmentation riddled with the same crystals that occur in the Gregariue. 



Spores of variable dimensions (inegaspores 24 /i, microspores 12/0) ovoid, distal 

 end neatly truncate, proximal end rounded; spores limited by a unique refringent 

 integument (endospore) situated at the extremities of small, very delicately walled 

 tubes, which latter form a sort of more or less undulating epispore. 



Spores arranged, at least in the large cysts, in a number of small, radial groups, 

 formed by the convergence of the tubes to a common center. Contents of young 

 spores granular ; of mature spores 8 falciform corpuscles (4 at each end), and a central 

 rest of segmentation. The falciform corpuscles are probably expelled on the death 

 of the host, and other Echinocardiums naturally become infected by swallowing the 

 sand containing them. 



Pigment identical with the products of dissimilation spread through the tissues 

 of the host; if specially condensed around the cysts, it is as a result of the [increased 

 tissue] expenditure necessitated by tlieir considei-able growth. 



The presence of small nodosities on the test could not be determined. 



The cysts, united into more or less voluminous masses, are surrounded by a con- 

 siderable mass of black pigment and of ama'boid cells, the latter A'ery evidently 

 Echinocardium amcebocytes accumulated around the foreign bodies. The latent life 

 of the cysts is probablj^ not very long, as there are frequently seen, apparently in 

 process of degeneration, small ones inclosing only empty spores absolutely devoid 

 of nuclei. 



As in all the other Monocystids studied, the Lithoci/stis spore has dissimilar poles, 

 the one truncate, the other rounded and furnished with a long tube. The structure 

 of the cysts is ai)preciably dilloreut from all other known Monocystids. 



