Altar fire

Literally, a fire on an altar; a sacrificial flame. Hence, figuratively, religious fervor, or any other deep sentimental emotion having the e ence of devotional zeal. Altern a'tion of Generation. ( Physiol.) A term under which it is here proposed to explain in detail the phenomena of non-sexual reproduction generally. This title does not correctly embrace all the phenomena of reproduction without the direct influence of the male, but until a more comprehensive general term be employed, it is certainly most convenient to describe these changes under the present head. It is in the lower animals only that we find the ordinary sexual reproduc tive proce superseded by the non-sexual production of individuals. Even in these the phenomena are com paratively rare. Neverthele they are by no means accidental, but, as Von Siebold remarks, have a definite position in the history of the development of organic beings, being especially manifested in the Cœlen terata; the cestode and trematode Entozoa, and in certain fami, lies of Insect a. Perhaps the true relation of the direct and indirect proce es of generation will be better under. stood by presenting all the phenomena of development in a tabulated form, as has been done by Prof. Huxley, thus: Development. Continous Disc on tin ous (Gemmation Growth. Metamorphosis. Gemmation (without fusion). (Agamogenesis... Parthenogenesis. Petren with fusion). (Gamogenesis. animals it is the immediate offspring of the individual developed from the ovum which resumes the sexual functions; in other animals this offspring bears a second brood, or a third, and even more succe ive generations, before the return is made to sexual reproduction." Such being a general statement of the facts representing so many links, as it were, in the complicated chain of phenomena of non-sexual reproduction, we now proceed to adduce a selection of illustrations by which this interesting law of alternate generation may be clearly understood. Probably the most practically useful exemplification which can be brought forward, is that which we derive from a consideration of the development of a cestode parasite or Entozoön which, unfortunately, infests the human body. In this view, therefore, we particularly invite attention to the natural history of the common Tape-worm, or Tænia solium. The Solitary Tape-worm (so misnamed from the false notion that only one lives in the same person at once), in the full-grown condition, is not, strictly speaking, a creature or animal, but rather a great many creatures attached to IMG:content-0455.png:[graphic] one another, so as to form a colony, or, more scientifically, the Strobila (See STROBILA, below.) This colony is usually composed of several hundred joints, and each of these joints represents an individual worm ( proglottis ); those which are nearest to the lower end (or so-called tail of the Tapeworm) being sexually mature. They are indeed hermaphroditic, i. e. having both male and female reproductive organs. Those feebly de veloped joints called neck of the which form the so- A, single joint or proglottis; B, head of worm are imper fect or immature individuals; whilst the little head is nothing more than a single individual (equivalent to a joint or proglottis) irregularly modified, and furnished with an apparatus by which the strobila or colony is, as it were, securely anchored to the walls of the bowel of the unhappy person which the Tape-worm infests. The man, woman, or child thus infested, or harboring the parasite, is technically said to be the host , because he or she entertains its presence. Looking, therefore, at the mature proglottis as the adult individual worm, we have now to consider the manner in which it reproduces itself. After the proglottis (which is furnished with male and female reproductive organs) has undergone impregnation by contact with another proglottis, there results from this the formation of eggs within it, which eggs, whilst still within the body of the parent, develop into embryos, the latter still retaining the egg coverings. At this time the proglottis is about to undergo a pa ive migration, for having detached itself from the strobila, it is soon expelled from the bowel of the host, and therefore finds its way into some ce pool, or it may be into the open fields. The proglottides move about for a time, but the growth of the multitudes of embryos within causes the proglottis sooner or later to burst, and the embryos thus become dispersed; some are thus conveyed down drains or sewers, others are lodged by the roadsides in ditches and waste places, whilst multitudes are scattered far and near by winds or insects in every conceivable direction. Each embryo is furnished with a special boring apparatus, having at its anterior end three pairs of hooks; the entire group or family, therefore, of any single proglottis is called the "six-hooked brood." After a while, by ac cident, as it were, a pig comes in the way, either of these embryos or of the proglottides, swallows them along with other matters taken in as food. The embryos, immediately being transferred to the digestive canal, escape from the eggshells and bore their way through the living ti ues of the animal, and having lodged themselves in the fatty parts of the flesh, they there rest to await their further transformation or destiny. The animal thus infested becomes measled, and thus it is that we are acquainted with measly pork. In this situation the embryos drop their hooks or boring apparatus, and become transformed into the Cysticercus cellulose. A portion of this measled meat being eaten by ourselves, either in a raw or imperfectly cooked con canal, in which situation the Cysticercus attaches itself to the wall of the human intestine, and, having secured The American Dictionary and Cyclopedia a good anchorage, begins to grow at the lower or caudal extremity, producing numerous joints or buds to form the strobila or Tape-worm colony. Thus the cycle of life-development is completed, and we have a simple alternation of generation in which the immediate product of the proglottis (or sexually mature individual) is a six-hooked brood; by metamorphosis the latter becomes transformed into the Cysticercus, having a head with four suckers, and a double crown of hooks; and by gemmation the latter gives rise to a whole colony (strobila) of individuals, the greater part of which are destined to become sexually mature individuals, or proglottides. It will be observed, therefore, that the product of a single ovum is in the first instance a single non-sexual embryo (or pro to zooid); in the second phase it becomes a non-sexual Cysticercus (or den to zooid); in the third change it gives off, by budding, numerous gemmules (or tri to zooids), most of them destined to be sexually mature individuals, and in this way to resemble their original parents. A more complicated alternation of generation occurs in the Cælen terata, especially in that division which we call the Hydrozoa. Thus the common zoöphyte Campanu taria may be taken as an example. Certain polyp like cells or gonoblastidia (f, Fig. 2660) of the polyp colony contain ova ( g ), which latter, after contact with spermatozoa developed from other cells, form ciliated embryos (i and c). These, having escaped from their gonoblastidium, swim about for a time, and, losing their cilia, ultimately settle down on some weed or rock, where, undergoing a change of form, they sprout upwards to form a young polypi do me (or coœnosarc). By a proce of gemmation numerous polyp-heads (polypites) are produced, and also at intervals other modified polypites, which are contained in similar capsules or hydrothecæ ( k and f). Some of these capsules give rise to medusoids ( 1 ) by a proce of budding, and these latter are capable of producing ova by an ordinary sexual proce (gamogenesis). Others form the gonoblastidia above mentioned, while the embryonic products of both these modified individuals form new polyp colonies in the way we have just described. If space admitted, wo should be glad to enter into minute details of this curiously complicated proce , a modification of which is seen in the development of certain Me 0097 Fig . 2660. 2 DEVELOPMENT OF CHRYSAORA. du e, such as Chrysaora. From these sexually mature forms Prof. Thomson has described the proce as follows:-"The fecundated ova which they produce are first developed into a ciliated moving animalcule (aand b, Fig. 2660), somewhat like a poly gastric an. This creature, after undergoing a slight change of form, fixes itself by the narrowest end, and acquires tentacles like a polyp at the other (c, d, and e), amounting for some time to eight (f). In this condition it appears to be capable of multiplying itself, or producing other similar attached polyps by gemmation from its side or base, or from a running stolon below it ( g ) . The subsequent change of each of these polypoids is remarkable. It has been described by Sars and Dalyell as follows:The body undergoing some elongation becomes partially divided by transverse grooves ( h , i) into a range or column of imperfect Meduse, attached still to each other by their adjacent surfaces, but presenting at their borders, in various degrees of advancement, the division into rays or lobes which belong to the Medusæ, the upper or terminal one having developed upon it a set of radiated proce es distinct from the tentacles of the polyp, and much longer than those of the rest ( k ). The young Medusæ are succe ively separated from the stock by the deepening of the transverse clefts between them (I). They then move about as independent animals, and proceed in their further growth and development to sexual and other completene (m, n). These bodies, therefore, are subject to two kinds of multiplication, which are very different: by simple gemmation a number or a colony of strobilsæ may be produced, and by transverse fi ion and development a number of Medusæ may be thrown off from each strobila." In the Tape-worm colony, as we have seen, the individuals of the strobila attain their sexual maturity while still a ociated together; but here, in the Medu e, the Meduse are very small and immature at the time of their separation. A still more startling modification of the non-sexual proce of reproduction is seen in the Plant lice or Aphides. In these tiny though highly organized insect members of the animal kingdom, whole generations, sometimes eleven in succe ion, are reproduced from sexual parents, all of them being the product of a single ovum. This is brought about by a proce of internal budding in the parents, the extruded viviparous young being developed internally from egg-like bodies, which are not true ova and have never undergone impregnation. The distinguished author above quoted describes the course of the generative proce as follows:-"Perfect male and female winged insects are observed only towards the autumn season. These fly about in great quantities; the impregnated females deposit their eggs, covered with a protecting case of mucus, in the axils and other rece es of plants, where they remain during the winter. In spring there are developed from these ova a brood of larvæ, or imperfect female Aphides, which soon produce, by an act of viviparous generation, and without any concurrence of the male sex, a progeny of a similar kind; and this is repeated in succe ive generations for nine or ten times in the common species, or for ten or twelve weeks during the summer, at the end of which time the last brood brings forth male and perfect female individuals, both of which die after having provided, by the production of fecundated ova, for the continued generation during the next season." In Fig. 2661, a shows the spermatozoön fertilizing the ovum (b), which gives rise to d, the first embryo or viviparous larva. This larva gives origin to eight somewhat differently formed larvæ (e), while each one of these in their turn produces eight others, and so on, until the succe ive progenies are completed; the last giving birth to true sexual individuals, a pair of which are here drawn, h being the male and ithe female. The multitudes of larval Plant-lice thus produced from a single ovum, though not defying calculation on paper, yet almost defy the imagination to conceive. This proce , while it constitutes a true parthenogenesis (q. v. below), is not only remarkable as occurring in creatures so high in the scale of animal organization, but also on account of the very close resemblance Fig . 2661. ILLUSTRATING THE DEVELOPMENT OF