Endospore

“ 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. ”

“ Most bacteria die if conditions become unfavorable to their growth, but some enter into a resting stage. This stage is characterized by the development of round or oval glistening bodies called spores, which are of dense structure and possess an extraordinary power to withstand heat, chemicals, and unfavorable surroundings. Except in rare instances a single cell produces but one spore. As soon as favorable conditions of temperature, moisture, and food supply are restored, the spore develops into the active form of the germ; it may, however, remain dormant [8] for months or years. ”

“ Now, a plant growing in the ground is similarly circumstanced to the bladder in this experiment: its roots furnished with extremities of spongy membrane are interposed between thin water and carbonic acid externally, and a syrupy solution of sugar and gum internally. Now, under those circumstances we need not be surprised if an endosmose should operate, abundantly sufficient to elevate the sap with a force even greater than that determined by Hales.
The use of the ascending sap in the vegetable economy is the last subject which we shall consider in this article. ”

“ 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 ”

“ The endoplasm is more fluid, and contains numerous inclusions of a granular nature, as well as vacuoles of varying size. In the endoplasm are lodged the nuclei, of which in an adult trophozoite there may be very many; they are all derived by multiplication from the single nucleus with which the young individuals begin life, the number increasing as growth proceeds.
Spore-formation goes on entirely in the endoplasm. The number of spores formed is very variable. ”

“ 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. ”

“ This inflow is called endosmosis, and the outflow of the solution is called exosmosis. If an indiarubber bottle be filled with water and immersed in alcohol or ether, the endosmosis of the spirit will be so powerfully exerted as to distend the bottle considerably. If the bottle be filled with alcohol or ether, and surrounded by water, it will nearly empty itself.
The force exerted by this action is displayed by the rising of the sap from the rootlets of a forest giant to the cells of its topmost leaves. Not only plants, but animals also, are complex osmotic machines. ”

“ Again, during the re-expansion of the tentacles, the glands secrete less freely, or quite cease to secrete, and the aggregated masses of protoplasm are then redissolved. Moreover, when leaves are immersed in dense vegetable solutions, or in glycerine, the fluid within the gland-cells passes outwards, and there is aggregation; and when the leaves are afterwards immersed in water, or in an innocuous fluid of less specific gravity than water, the protoplasm is redissolved, and this, no doubt, is due to endosmose. ”

“ 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. ”

“ This ascending sap is not so viscid a liquid as that contained in the cells: thus, the syrupy contents of the latter must, according to the principle of endosmose described in a previous article, absorb into the cells the ascending sap, in a way similar to that whereby syrup placed in a bladder, immersed in a basin of water, will attract the latter liquid through the membrane, until the bladder be filled. While the sap continues to ascend, therefore, the cells must necessarily continue swollen in proportion to their size. ”

“ In each chamber is a pansporoblast, which divides up to produce many spores; hence the spores formed from different pansporoblasts are kept more or less separate. The pansporoblasts originate, in a growing Sarcosporidian, at the two poles of the body, where the peripheral endoplasm with its nuclei is chiefly aggregated. More internally, spore-formation is in progress; and in the centre, pansporoblasts full of ripe spores are found. ”

“ If we take Entozoa generally, they may be considered as most conveniently to be placed in this intermediate class; and here we find still the digestive apparatus, and more than this,—for upon the modifications of the organs appropriated to digestion is their classification founded. "Rudolphi divided the Entozoa into Sterelmintha, or those in which the nutrient tubes without anal outlet are simply excavated in the general parenchyma, and into the Cœlelmintha, in which an intestinal canal with proper parietes floats in a distinct abdominal cavity, and has a separate outlet for the excrements." ”

“ Under favorable conditions bacteria multiply rapidly, but when conditions are unfavorable, they take on a spore formation and remain in a quiescent state, like the seed of a plant, waiting—it may be years—until proper conditions are present. The spores are protected by such a thick envelope and have such great potential vitality, that it is much more difficult to kill them than the developed bacteria. ”

“ Sporulation only takes place outside the body, probably because free oxygen is necessary to the process. In the spore-free condition, the organisms are readily destroyed by ordinary germicides, and by the gastric juice. The spores, on the other hand, have a high degree of resistance. ”

“ From the above description it follows that the spore is to be considered as a condensation of the bacterial protoplasm surrounded by an especially thick cell wall. Its function is the preservation of the organism under adverse conditions. It corresponds most closely to the encystment of certain protozoa—the ameba for example. Possibly the spore represents a very rudimentary beginning of a reproductive function such as is gradually evolved in the higher thread bacteria, the fission yeasts, the yeasts, the molds, etc. ”

“ The nucleus of each spore next divides, again directly, and this is followed by the division of the cytoplasm. As a final result, each of the four spores contains two germs (sporozoites) , and a certain amount of residual protoplasm (fig. 3, IV.) ; this latter encloses a viscid, vacuole-like body, which aids in the subsequent dehiscence of the sporocyst. On being eaten by a fresh host, the wall of the oocyst is dissolved at a particular region by the
digestive juices, which are thus enabled to reach the spores and cause the rupture of the sporocysts. ”

“ 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. ”

“ When the conditions are again favourable, spores germinate, giving rise to new bacilli. The germinating spore becomes elongated, and loses its bright appearance, the outer membrane becomes ruptured, and the young bacillus is set free. Certain conditions, such as the presence of oxygen in the case of the anthrax bacillus, give rise to the formation of spores; while various kinds of bacteria secure continuous existence by developing spores when there is lack of proper food material. ”

“ Sometimes, owing to external conditions, such as lack of food certain bacteria produce spores. The power of spore formation is not possessed by all bacteria and those which are able to bring it about are difficult to kill for the spores, which contain the living material of the bacterium are surrounded with walls which will resist boiling, drying, freezing and all manner of ill treatment. ”

“ The fact that the protoplasm is denser and the spore capsule thicker (the percentage of water in each is decidedly less than in the growing cell) gives the spore the property of much greater resistance to all destructive agencies than the active bacterium has. For example, all actively growing cells are destroyed by boiling in a very few minutes, while some spores require several hours’ boiling. ”

“ In some states of prostration, where the blood is insufficiently supplied with these juices, this endosmosis is like pouring new life into the body, but it is not what is required for the normal sustenance of the healthy body. ”

“ Spores are formed by some bacteria when they are subjected to an unfavorable environment such as high temperatures, the absence of food, the absence of moisture, etc. Spores are cells in which growth and animation are suspended but the life of the cell is carried on through the unsuitable period, somewhat similar to the condition in a plant seed. ”

“ 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. ”

“ The mouth is placed some distance from the anterior end in an oral depression and opens into a tubular œsophagus. There are usually two undulating membranes which do not extend beyond the mouth borders. The right undulating membrane extends down into the œsophagus and appears to be attached to the walls of the latter. The body stripes in front of the mouth are twisted to the left. The anus is terminal and the contractile vacuole may be terminal or situated forwards in the dorsal region. The macronucleus is spherical and has one micronucleus attached. Food consists mainly of bacteria. ”

“ This of course was simply the effect of endosmosis. Mr. Couch, in describing the moulting of the common Edible Crab (Cancer Pagurus) , speaks of its drinking large quantities of water, and thus becoming distended; but I rather think that the distension takes place by endosmosis, even during life. There are two circumstances which militate against Mr. Couch's opinion:—first, the rapidity with which the distension occurred in the Crab I have just exhibited, while still in the act of moulting ”

“ ECTOSPORA, a homogeneous and natural division of Protozoan parasites included under the Sporozoa; they comprise the three orders, Gregarines, Coccidia and Haemosporidia. The defining character of the Ectospora is that the spore-mother-cells (sporoblasts) are formed at the periphery of the parent-individual (sporont) ; we may, however, go further, and say that the formation of all the different reproductive elements is uniformly peripheral or exogenous. ”

“ Fig. 10.—Bacillus subtilis. (After Strasburger.) A. Zoogloea pellicle. B. Motile rodlets. C. Development of spores.
The spore may be formed in short or long segments, the cell-wall of which may undergo change of form to accommodate itself to the contents. As a rule only one spore is formed in a cell, and the process usually takes place in a bacillar segment. In some cases the spore-forming protoplasm gives a blue reaction with iodine solutions. The spores may be developed in cells which are actively swarming, the movements not being interfered with by the process (fig. 4, D) . ”

“ If you substitute solid particles, or things that will not dissolve, you will find no change. This property which membranes, such as a bladder, have, is called osmosis. It is by osmosis chiefly that the raw, nourishing material in the blood gets into the flesh lying about the capillaries. It is by osmosis chiefly that food gets out of the stomach into the blood. It is by this property that the worn-out materials are drained away from the blood, and so cast out of the body. By osmosis the blood nourishes and purifies the flesh. By osmosis the blood is itself nourished and kept pure. ”

“ For this spore, though so small as to be visible only by microscopic aid, had a previous history, which may be traced without difficulty. It was generated with hundreds [Pg 118] more, in one of many capsules, which, were crowded together, beneath the oval bit of membrane, that covered one of the brown spots (sori) , which were developed in the under surface of the fronds of an earlier Lady-fern. That earlier individual had in turn passed through the same stages of sporal frond, prothallus, spore, theca, sorus, frond, prothallus, spore, theca, sorus, frond, prothallus, &c.—ad infinitum. ”