JcNE 2, 1882.] 



• KNOWI.EDGE 



accordance with natural history usage, are apt to 

 convey what he is pleased to call an " erroneous 

 impression." He remarks that the whale is a " Mammal," 

 but not a "Quadruped" — meaning, of course, that 

 a whale has not four legs. Dr. Fisher may, perhaps, 

 have heard the remark tliat a good deal in this world 

 depends upon one's point of view ; and his point of view 

 happens in this case not to be mine. I carefully explained 

 that I used the terms " Quadruped " and " Mammal " as 

 convertible names, and this for the reason that in zoology 

 — as, indeed, in every-ciay life — the names are so em- 

 ployed. Has Dr. Fisher ever heard of a frog (one of 

 his examples) Vieing called a " Quadruped," in the same 

 breath with an ox- And does he not know that a 

 whale possesses all the essential characters of quadruped- 

 life which he himself rejoices in the possession of ? 

 As to a whale not possessing four limbs, perhaps 

 Dr. Fisher, not being a zoologist, is not aware that 

 in some whales {i-.g., the whalebone genus, or Bahma) 

 there are actual representatives, not merely of the haunch- 

 bones, but of the thighs as well. Hence, a whale may 

 claim to be a quadruped, even although its hind-Umbs are 

 rudimentary. Dr. Fishers somewhat querulous objections 

 are overruled by the fact, that, as I started by defining 

 " Quadrupeds " and " Mammals " as being one and the 

 same, the scientific meaning (and, as I maintain, the 

 popular raeaning also) of these terms is not likely to Vie 

 mistaken liy any reader of ordinary intelligence. It is 

 true, as Dr. Fisher remarks, that in many mammals, the 

 clavicles, or collar-bones, are wanting, just as these bones 

 are absent in some members of an order (e.g., rcdents) and 

 present in others : or, as is the case with the guinea-pigs 

 and rabbits, the clavicles may be wanting at birth, and 

 become developed later. What I indicated in my paper 

 (Knowledge, No. 2.5) was the typical condition of the 

 quadruped shoulder. If Dr. Fisher maintains that it is 

 more typical for a quadruped to want collar-bones than to 

 possess them, that is his affair. He is not likely to find 

 any comparative anatomist to agree with him. 



In the present paper I purpose to give an outline of the 

 means wliereby the zoologist has been enabled to supply 

 " links " between the Vfrtebratr, or " backboned " animals, 

 and the Inverfebrati:, or "boneless" animals. Ever since 

 the time of Lamarck, the distinction between the highest, 

 or Vertebrated animals (fishes, frogs, reptiles, birds, and 

 mammals or quadrupeds) and the Invertebrate groups, has 

 been recognised as one of very clear nature. And modern 

 zoologj-, dealing merely with the structure of the animals 

 in question, fully recognises the apparent gap which inter- 

 venes between the great array of boneless animals — such 

 as -worms, insects, shell-fish, itc. — and the " backboned " 

 group. But, as in many other cases, a closer examination 

 of the lowest Vertebrate group seems to demonstrate that 

 the gulf between the highest animals and their Invertebrate 

 neighbours is by no means so wide or impassalile as, at first 

 sight, it appears to be. The lowest fish and Vertebrate is 

 the Ani/'/iioxus, or Lancelet (Fig. 1). Tliis is a little clear- 

 bodied fish — formerly regarded as a kind of slug — found 

 inhabiting sand-banks in various quarters of the world. 

 It attains a length of an inch or two, and is pointed 

 at each end. It has a kind of back and tail tin, but 

 possesses none of the " paired " fins, wliich, existent in most 

 other fishes, represent the limbs of higher animals. The 

 moutli {<•) is an oval slit, and is fringed with gristly fila- 

 ments. The lancelet has no brain, heart, bones, skull, eai-s, 

 or kidneys. It is the only vertebrate which wants a heart, 

 and it is likewise the only vertebrate in which the blood is 

 colourless. Along the back runs the only representative 

 of the skeleton — namely, a soft rod-like body, called the 



notochord (n). This structure, by the way, is found in the 

 early development of every vertebrate animal, being re- 

 placed in all, save a few fishes, as time passes, by the spine 

 itself. Above this rod lies the nervous cord of the lancelet. 

 The mouth opens into a very wide throat or j/hari/n.r 

 (b), whose walls are perforated with slits that open into 

 the cavity of the body. The walls of this great throat are 

 richly set with the microscopic processes called cilia, which, 

 by their incessant waving, circulate the water admitted to 

 the cavity. The throat leads into a simple stomach (g), and 



Fig. 1. — The Lancelet (Amphiozus laneeolatus), enlarged to twice 

 its natural size, (o Month ; i> Enlarged pharynx ; <7 Stomach ; 

 ■h Sac representing the liver ; » Intestine; a Anus; n Notochord ; 

 / Eudiments of tin-rays ; p Abdominal pore). 



this, in turn, leads into the intestine (;). A liver (/<) of the 

 most rudimentary description also exists. The blood, in the 

 absence of a heart, is circulated by the contractions of the 

 bloodvessels, and it is interesting to note that the arrange- 

 ment seen in all vertebrates, whereby a portion of the 

 venous, or impure blood, is sent to the liver for the manu- 

 facture of bile, is represented even in this curious fish. 

 When the lancelet breathes, v.-ater is received into the 

 throat, passes over the network of bloodvessels in the 

 walls thereof, and after giving up its oxjgen to the blood, 

 is sent by the cUiary action through the slits in the throat 

 into the body cavity. Thence it is expelled through a 

 small opening near the tail, and called the abdominal 

 pore (j)). 



The lancelet differs from every other vertebrate animal 

 in the absence of a heart, skull, brain, and kidneys, and in 

 the colourless blood : in tlie peculiar and rudimentary liver ; 

 and in a digestive system, which, like the throat, is also 

 lined with cilia. But that it is a vertebrate is proved by 

 the presence of the notochord (»), already remarked as being 

 developed in the early life of every vertebrate animal. 

 The supply of venous blood to the liver is also a vertebrate 

 character ; whilst its development, studied from the egg 

 onwards, no less clearly shows its right and title to be 

 regarded as a true vertebrate. 



HOME CURES FOR POISONS. 



^TO one who is wise will fail to send at once for a doctor 

 1\ when poison has been taken, eitlier by inadvertence 

 or otherwise. But there arc often remedies or antidot4'S 

 close at hand, which may be of great use, even to the saving 

 of life, if taken at once. It is not with any idea of 

 encouraging people in such cases to do without the doctor, 

 but to indicate certain home cures for even the most violent 

 poisons, to which recourse can be had before he comes, 

 that we write this series of short papers. There are cases 

 in which the nature of a poison taken inadvertently can be 

 determined at once, when therefore the proper home cure, 

 if such there be, is at once known. Then' arc other cases 

 in wliich, though it be not known what poison has been 

 taken, tlie symptoms presently show at least the class of 

 poisons to which the substance Iwlongs ; in many such 

 cases the remedy is as certainly indicated as though the 



