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
  • 宣和画谱

    宣和画谱

    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。
  • 金箓十回度人午朝转经仪

    金箓十回度人午朝转经仪

    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。
  • 佛说如来智印经

    佛说如来智印经

    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。
  • The Outlet

    The Outlet

    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。
  • 戒子通录

    戒子通录

    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
  • 美女瘦身食谱

    美女瘦身食谱

    想成为君子好逑的窈窕淑女吗?想拥有楚腰燕瘦的身材吗?吃也是可以成就一个美女的。爱美之心人皆有之,谁都想拥有完美身材,展现自身魅力。遇到体重“超标”了就着急减肥,但是忽视了减肥的科学性,所以提倡需要减肥的白领女性选用科学减肥方法。这本书针对女性的工作、生活特点,推荐了一些减肥食谱,同时也要结合运动减肥。
  • The Coming Race

    The Coming Race

    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。
  • 斗破苍穹之古帝传奇

    斗破苍穹之古帝传奇

    斗气大陆,势力飞卢,精英辈出,其中最为令人羡慕的职业便是——炼药师。众所周知,炼药师最需要的便是火焰,而异火,便是其中的翘楚之辈。异火现,万火臣服。一簇异火,诞生于天地之间,千年成形,冥冥中自有几分变异,使得此火不如其他异火一般留守诞生之地,却是主动离开,游离于地底岩浆之中。神秘异火,成帝之谜。且看此火如何在残酷的异火吞噬中成就帝位,演绎传奇。
  • 普京的男人法则

    普京的男人法则

    本书首次全面揭秘强人普京的22大男人法则,彰显普京刚柔并济的人格魅力、拼搏奋斗的人生历程、铁血柔情的王者风范,让每一位男人都能成为内外皆修、卓越非凡的完美男人。
  • 长相思(全集)

    长相思(全集)

    何谓相思?思而不得,最相思。相爱是两个人的天长地久,相思却是一个人的地老天荒。桐华唯美大气爱情经典之“山海经纪”系列完结篇。上古时代,神族、人族、妖族混居于天地之间。盘古大帝仙逝后,战火频起,经过数万年的变迁,大荒逐渐形成了中原的神农、东南的高辛、西北的轩辕,三大神族,三分天下。轩辕黄帝雄才伟略,经过和神农族的激烈斗争,统一了中原,可一切矛盾犹如休眠的火山,随时会爆发。清水镇上的小医师玟小六无意中救了一个几乎半死的叫花子,却不料此人竟是世代经商的涂山世家的公子涂山璟。玟小六的身份也不是普通医师这么简单,在此期间,玟小六又结识了神农义军将领相柳,并和自小分离的表哥玱玹重遇,几人之间的牵绊日益加深,最终也影响了整个大荒的命运,谱就一曲荡气回肠的相思曲。
  • 极品小医师

    极品小医师

    七星诡针传人秦川为找有缘人来到都市,凭借逆天医术,来拯救深陷水火之中的人们。医生会武术,美女站不住。少年神医都市行,医德仁心救苦难,名扬天下传四海。
  • Tales of Troy

    Tales of Troy

    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。
  • 东家,你嘴里叼的是姑娘

    东家,你嘴里叼的是姑娘

    后来,安平县的说书人经常讲谢家酒馆的老板是怎么被人坑,怎么被人蒙,怎么被人拐,怎么被骗,最后被人怎么压的故事。然而,真相应该是谢家酒馆的老板坑人,蒙人,拐人,骗人,然后压人的故事。阿酒:东家,他们为什么都对咱们指指点点的?谢春深(怒):我才不知道为什么呢!阿酒:哦。谢春深内心:呼!我才不告诉你他们认为咱俩是断袖……情节虚构,切勿模仿
  • 谍影重重

    谍影重重

    《谍影重重》间谍的主要任务之一,就是采取非法或合法手段、通过秘密或公开徐径窃取情报,也进行颠覆、暗杀、绑架、爆炸、心战、破坏等隐蔽行为;被派谴或收买来从事刺探机密、情报或进行破坏活动。
  • 武歌记

    武歌记

    二十年前,名不经传的黑衣剑客手持七星剑,横扫北域各路英雄豪杰。在与第一剑客王百剑大战了三天三夜后,销声匿迹。二十年后,武学天赋平凡的武歌,因祸得福,捡到了七星剑,从此展开不一样的人生…