登陆注册
5158700000011

第11章

When an anterior gland contains several minute concretions, some of these are generally angular or crystalline in outline, while the greater number are rounded with an irregular mulberry-like surface.Calciferous cells adhered to many parts of these mulberry-like masses, and their gradual disappearance could be traced while they still remained attached.It was thus evident that the concretions are formed from the lime contained within the free calciferous cells.As the smaller concretions increase in size, they come into contact and unite, thus enclosing the now functionless lamellae; and by such steps the formation of the largest concretions could be followed.Why the process regularly takes place in the two anterior glands, and only rarely in the four posterior glands, is quite unknown.Morren says that these glands disappear during the winter; and I have seen some instances of this fact, and others in which either the anterior or posterior glands were at this season so shrunk and empty, that they could be distinguished only with much difficulty.

With respect to the function of the calciferous glands, it is probable that they primarily serve as organs of excretion, and secondarily as an aid to digestion.Worms consume many fallen leaves; and it is known thatlime goes on accumulating in leaves until they drop off the parent-plant, instead of being re-absorbed into the stem or roots, like various other organic and inorganic substances. The ashes of a leaf of an acacia have been known to contain as much as 72 per cent.of lime.Worms therefore would be liable to become charged with this earth, unless there were some special means for its excretion; and the calciferous glands are well adapted for this purpose.The worms which live in mould close over the chalk, often have their intestines filled with this substance, and their castings are almost white.Here it is evident that the supply of calcareous matter must be super-abundant.Nevertheless with several worms collected on such a site, the calciferous glands contained as many free calciferous cells, and fully as many and large concretions, as did the glands of worms which lived where there was little or no lime; and this indicates that the lime is an excretion, and not a secretion poured into the alimentary canal for some special purpose.

On the other hand, the following considerations render it highly probable that the carbonate of lime, which is excreted by the glands, aids the digestive process under ordinary circumstances.Leaves during their decay generate an abundance of various kinds of acids, which have been grouped together under the term of humus acids.We shall have to recur to this subject in our fifth chapter, and I need here only say that these acids act strongly on carbonate of lime.The half-decayed leaves which are swallowed in such large quantities by worms would, therefore, after they have been moistened and triturated in the alimentary canal, be apt to produce such acids.And in the case of several worms, the contents of the alimentary canal were found to be plainly acid, as shown by litmus paper.This acidity cannot be attributed to the nature of the digestive fluid, for pancreatic fluid is alkaline; and we have seen that the secretion which is poured out of the mouths of worms for the sake of preparing the leaves for consumption, is likewise alkaline.The acidity can hardly be due to uric acid, as the contents of the upper part of the intestine were often acid.In one case the contents of the gizzard were slightly acid, those of the upper intestines being more plainly acid.In another case the contents of the pharynx were not acid, those of the gizzard doubtfully so, while those ofthe intestine were distinctly acid at a distance of 5 cm.below the gizzard.Even with the higher herbivorous and omnivorous animals, the contents of the large intestine are acid."This, however, is not caused by any acid secretion from the mucous membrane; the reaction of the intestinal walls in the larger as in the small intestine is alkaline.It must therefore arise from acid fermentations going on in the contents themselves...In Carnivora the contents of the coecum are said to be alkaline, and naturally the amount of fermentation will depend largely on the nature of the food."

With worms not only the contents of the intestines, but their ejected matter or the castings, are generally acid.Thirty castings from different places were tested, and with three or four exceptions were found to be acid; and the exceptions may have been due to such castings not having been recently ejected; for some which were at first acid, were on the following morning, after being dried and again moistened, no longer acid; and this probably resulted from the humus acids being, as is known to be the case, easily decomposed.Five fresh castings from worms which lived in mould close over the chalk, were of a whitish colour and abounded with calcareous matter; and these were not in the least acid.This shows how effectually carbonate of lime neutralises the intestinal acids.When worms were kept in pots filled with fine ferruginous sand, it was manifest that the oxide of iron, with which the grains of silex were coated, had been dissolved and removed from them in the castings.

The digestive fluid of worms resembles in its action, as already stated, the pancreatic secretion of the higher animals; and in these latter, "pancreatic digestion is essentially alkaline; the action will not take place unless some alkali be present; and the activity of an alkaline juice is arrested by acidification, and hindered by neutralization." Therefore it seems highly probable that the innumerable calciferous cells, which are poured from the four posterior glands into the alimentary canal of worms, serve to neutralise more or less completely the acids there generated by the half-decayed leaves.We have seen that these cells are instantly dissolved by a small quantity of acetic acid, and as they do not always suffice to neutralise the contents of even the upper part of the alimentary canal, thelime is perhaps aggregated into concretions in the anterior pair of glands, in order that some may be carried down to the posterior parts of the intestine, where these concretions would be rolled about amongst the acid contents.The concretions found in the intestines and in the castings often have a worn appearance, but whether this is due to some amount of attrition or of chemical corrosion could not be told.Claparede believes that they are formed for the sake of acting as mill-stones, and of thus aiding in the trituration of the food.They may give some aid in this way; but I fully agree with Perrier that this must be of quite subordinate importance, seeing that the object is already attained by stones being generally present in the gizzards and intestines of worms.

同类推荐
  • 长生殿

    长生殿

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 成唯识宝生论

    成唯识宝生论

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 答陆澧

    答陆澧

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 梁武帝演义

    梁武帝演义

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 檀弓上

    檀弓上

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
热门推荐
  • 大小姐的田园生活

    大小姐的田园生活

    她的生活轨迹应该是安静的绣着嫁衣,等着未婚夫在良辰吉日将她迎娶回家。谁知道一夜之间,未婚夫没了,爹娘也葬身在火海之中。只能在侍卫的保护下带着才七个月大的幼弟逃离京城,去到侍卫的家乡隐姓埋名,只是……
  • 网游之归来王者

    网游之归来王者

    他原是电竞界最闪耀的新星,本来应该光芒万丈,但是却在一次赛事上失误而退出电竞神坛,如今他又卷土重来,能否再现昔日辉煌。
  • 左手赚钱右手花钱

    左手赚钱右手花钱

    本书从树立正确的理财观念说起,着重介绍了各种理财方式和技巧,例如本书所阐述的关于储蓄、*、股票、保险、外汇、期货等基本知识,希望能够给各位读者带来一些启迪。每个人都有致富的机会,希望每个读者都能够从本书中有所收获,学会挣钱,更要学会花钱,从而快乐而轻松地实现致富的愿望,享受快乐丰足的财富人生。
  • 一切都是为了那个太监男主

    一切都是为了那个太监男主

    这是一个暴力吃货公主和阴柔狠辣太监不得不说的二三事。你穿越到不知名的朝代成为一个前途大大滴好的公主,你可以在这个世界横着走竖着走倒着走躺着走想咋滴就咋滴,但你做的一切,都是为了你的男主。
  • 狼犬大人,别过来

    狼犬大人,别过来

    苏亦眠梦到自己被一堆零食活埋了...不是撑死,也不是噎死,居然是被活活憋死!估计她是世间第一人...忽天降下一狼犬,那厮以救她为诱饵,骗她签订契约,美其名曰能相互感应(灵犀)...戴上指环之后,苏亦眠:尼玛我怎么感觉像签了一份卖身契??!
  • 刀镇乾坤

    刀镇乾坤

    当东西方神话里的人重现,当斗气魔法出现,当科技与修真同存……一根试管婴儿胚胎,一场地震,50亿年后这个试管婴儿出世!整个银河星系乃至其它各星系都因他而发生惊天巨变!
  • 愿你眼眸似星辰

    愿你眼眸似星辰

    商煜用十年的时间,为仇人的女儿编织了一个完美的梦,自以为自己是站在黑暗顶端俯视这场噩梦的人,殊不知自己的对手比他更加高明。苏络爱惨了商煜,却亲眼看着最爱的人毁掉自己的一切,将她从云端打入了谷底。报复一个背叛过你的男人最佳方法是什么?苏络:让他真的爱上你,然后……然后我也不知道该如何……--情节虚构,请勿模仿
  • 明伦汇编人事典命运部

    明伦汇编人事典命运部

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 抗病人生

    抗病人生

    这虽说是“我”的经历,但也不完全是自说自话的诉说,因为就如书中所说“不仅帮助身体有疾病的人,而且帮助在这个物欲烦燥的世界上心理有疾病的人。能帮助到人并传递正能量是我最开心的事!”也许,人们在“我”身上看不到完美,但“我”想让人们通过“我”看到希望。
  • 萧红小说集

    萧红小说集

    被誉为“30年代的文学洛神”的萧红,是民国四大才女中命运最为悲苦的女性,也是一位传奇性人物。本书精选了萧红的小说代表作《呼兰河传》《生死场》《小城三月》等。萧红的作品以抒情笔调抒写着自我主观感受;散文化的小说结构;重文化风俗和自然景物的描写,不在人物性格的刻画上浪费笔墨;故事情节断断续续,然而意味深长;童年趣事,妙趣横生。正如茅盾先生给出的评价:“有讽刺,也有幽默。开始读时有轻松之感,然而愈越下去心头就会一点一点沉重起来。可是,仍然有美,即使这美有点病态,也仍然不能不使你炫惑。”