Harold Mellor Woodcock

“ Order—Haplosporidia. The Sporozoa included in this order are characterized by the general simplicity of their development, and by the undifferentiated character of their spores. The order includes a good many forms, whose arrangement and classification have been recently undertaken by Caullery and Mesnil (15) , to whom, indeed, most of our knowledge relating to the Haplosporidia is due. The habitat of the parasites is sufficiently varied; Rotifers, Crustacea, Annelids and fishes furnishing most of the hosts. ”

“ ENDOSPORA, a natural group or class of the Sporozoa, consisting of the orders Myxosporidia, Actinomyxidia, Sarcosporidia and Haplosporidia, together with various insufficiently-known forms (Sero- and Exosporidia) , regarded at present as Sporozoa incertae sedis. ”

“ The valves are usually prolonged into processes or appendages, whose form and arrangement characterize the genus; but in Sphaeractinomyxon the spore is spherical and lacks processes. The sporoplasm may be either a plasmodial mass, with numerous nuclei, or may form a certain number of uninuclear sporozoites. A remarkable feature in the development of the spore is that the germinal tissue (sporoplasm) arises separate from and outside the cellules which give rise to the spore-wall; later, when the envelopes are nearly developed, the sporoplasm penetrates into the spore. ”

“ Most forms attack the intestinal wall, often destroying its epithelium over considerable areas; but one genus, Sphaeractinomyxon, inhabits the body-cavity of its host. The researches of Caullery and Mesnil (10-12) and of Léger (28 and 29) have shown that the parasites exhibit the typical features of the Endospora, and the spores possess the characteristic polar-capsules of the Myxosporidian spore, but differ therefrom by their more complicated structure. ”

“ The seat of the invasion and the mode of parasitism are extremely varied. Practically any organ or tissue may be attacked, excepting, apparently, the testis and cartilage and bone. In one instance at least (that of Nosema bombycis of the silkworm) the parasites penetrate into the ova, so that true hereditary infection occurs, the progeny being born with the disease. The parasites may be either free in some lumen, such as that of the gall bladder or urinary bladder (not of the alimentary canal, or the body-cavity itself) , when they are known as coelozoic forms ”

“ The most noticeable feature about the Myxosporidian trophozoite is its amoeboid and Rhizopod-like character. Pseudopodia of various kinds, from long slender ones (fig. 3, B) to short blunt lobose ones, are of general occurrence, being most easily observed, of Morphology. course, in the free-living forms. The pseudopodia serve chiefly for movement and attachment, and never, it should be noted, for the injection of solid food-particles, as in the case of Amoebae. The general protoplasm is divisible into ectoplasm and endoplasm. ”

“ Spores relatively large, with generally two or four polar-capsules, visible in the fresh condition. There are nearly always two spores formed Classification. in each pansporoblast.
Section (a) : Disporea. Only two spores (i.e. one pansporoblast) produced in each individual trophozoite. The greatest length of the spore is at right angles to the plane of the suture.
One family, Ceratomyxidae, including two genera, Ceratomyxa (fig. 3, B) and Leptotheca, typically “free” parasites, mostly from the gall bladders of fishes. ”

“ Each is of quite simple, undifferentiated structure, possesses a large, easily-visible nucleus, and gives rise in due course to another young trophozoite. In some instances, as described by Minchin, the sporulating parasite becomes rounded off and forms a protective cyst, doubtless for the protection of the spores during dissemination. ”

“ It may be as low as two (as in free-living forms, e.g. Leptotheca) , in which case a large amount of trophic protoplasm is unconverted Spore-formation; multipli-cative processes. into spores; or, on the other hand, the number of spores may be very great (as in tissue-parasites) , practically the whole of the parent-body being thus used up. The sporont may or may not encyst at the commencement of sporulation. In the free-living forms there is no cyst-membrane secreted ”

“ Spores with two polar-capsules, and without an iodinophilous vacuole in the sporoplasm. Mostly “free” parasites. Gen. Sphaerospora. Four or five species are known, from the kidneys or gall bladder of fishes (fig. 3, A) . One, S. elegans, is interesting in that it affords a transition between the two sections, being disporous. Gen. Myxidium; spores elongated and fusiform, with a polar capsule at each extremity. The best-known species is M. lieberkühnii, from the urinary bladder of the pike. One or two species occur in reptiles. ”