Vol. XXtll. No. 2.] 



POPULAR SCIENCE NEWS. 



19 



taken place in respect to skill in action depending 

 upon powers of intelligence, (instincts) but also in 

 ivspect to bodily structure. Among men skill is 

 altogether a matter of education of hand and mind; 

 ill the.se animals there is not only the skill of edu- 

 cation — inherited instincts — but also that which 

 comes from perfect adaptation of organic structure. 

 Ifydroids. — Probably the most remarkable in- 

 stance of division of labor among animals is that of 

 the hydroid zoophytes. This case is not generally 

 known and may merit a somewhat carelul descrip- 

 tion. The hydroids are very small plant-like ani- 

 mals living in sea-water attached to rocks, shells, 

 sea-weeds, etc. There are very important species, 

 all of which to a greater or less extent illustrate the 

 principle under consideration, We may select for 

 description the species always found attached to the 

 shell of the hermit-crab, viz: Ilydraclinia. The 

 animal is of compound form, consisting of a colony 

 of different members, or zooids, orgapically united 

 In- a common base. The accompanying figure 

 sliows the structure of the body; it is seen that 

 tliere are three distinct kinds of zooids', (a, 4, c,) 

 lOach of these has its special function to perform in 

 tliL' life of the animal. To one class, (a), called 

 nutritive zooids, is allotted the task of obtaining 

 a lul digesting food. The mouth is at the free end, 

 and is surrounded bv a circle of tentacles which are 



organs tor capturing prey. The food-matter having 

 been swallowed, it then undergoes digestion within 

 the body of the nutritive zooid, whence it is dis- 

 tributed to the other members of the colony. A 

 second set of zooids (i) is concerned with the re- 

 production of the species, these members, therefore, 

 being termed reproductive zooids. At first they 

 do not differ in structure, and probably not in func- 

 tion, from the nutritive zooids, but after a time a 

 circle of buds grows out beneath the tentacles which 

 eventually develop the reproductive elements, giv- 

 ing to the members of the commnnity a distinctive 

 sexual character. The third class of zooids (c) have 

 as their special duty the defen.se of the entire colony 

 and are called protective zooids. Their bodies are 

 capable of extension and flexion, so as to enable 

 them to keep guard over the community. The free 

 end of the body is abundantly provided with minute 

 stinging organs called neniatocysts or thread-cells, 

 being identified in structure and manner of action 

 to those of jelly-fishes. 



This remarkable instance of division of labor is 

 the more notable in that it occurs among animals 

 of very low grade of organization. It indicates 

 strongly that this principle is a fundamental one in 

 the economy of animal life. It is interesting to 

 'note, too, that in these low animals the several 

 functions distributed to different members of the 

 (colony are precisely the same as those which are 

 distributed to the several classes in an insect com- 

 Unimity. In other words, those offices which in a 

 •compound hydroid are distributed to the different 

 ;parts of the body of one individual animal are, in 



the insects, ^aninuils of comparatively high rank 

 — distributed to dilferent classes of animals, which 

 together make one community. 



The Animal Body Ilself. — Finally, it is specially 

 to be noted that, excepting the -lowest, unicellular 

 animals, the body of any animal affords an exem- 

 plifi(;ation of the principle of division of labor. 

 The several activities which together constitute the 

 life-processes of the body are performed by dift'er 

 ent tissues, organs, or systems of organs, each of 

 which is fitted to carry on its own particular lab«5r 

 and none other. The eye is fitted to see, the heart 

 to propel the blood, the stomach to digest, the 

 brain to perceive, etc. Or, if we take related or- 

 gans in their connection we have the alimentary 

 .system performing one function, the circulatory 

 system another, the -nervous system another, etc. 

 That is to say, in the animal body there is a more 

 minute division of occupations : Some general 

 functions, e. g. alimentation, is assigned to one set 

 or system of organs, and then the labor of this func- 

 tion is resolved into special torms of activity which 

 are allotted to the dift'erent organs constituting the 

 system. Thus in alimentation, one duty is per- 

 formed by the teeth, another by the stomach, an- 

 other by the intestines, etc. A parallel can there- 

 fore be drawn between the activities of civilized hu- 

 man society and the physiological activities of any 

 of the higher animals. As in hiunan society there 

 are several general industries, agriculture, com- 

 merce, etc., each of which is divided into special 

 trades and colleges, so in the animal body there are 

 general functions each of which is divided into spe- 

 cial kinds of action. Or, another parallel may be 

 drawn between the differentiation of occupations as 

 a barbarous community Advances into civjlized so- 

 ciety, and the differentiation of functions as we pass 

 from the lowest animals to those highest in the 

 scale of life. 



B'inally, it is to be noted tliat the several general 

 functions of the highly organized animal body — 

 those functions that are distributed to the different 

 systems of organs — are themselves reducible to the 

 three primary functions which form a basis for a di- 

 vision of labor in a compound hydroid animal and 

 in a commimity of ants or bees. Thus, in the high 

 animal, digestion of tbod, circulation of blood and 

 excretion of waste — functions performed by differ- 

 ent sets of organs — are after all only parts of the 

 one labor of nutrition performed by these sets of 

 organs acting in association ; other organs and tis- 

 sues eft'ect the function of reproduction, and. finally, 

 all the parts and organs belonging to the nervous 

 systein are, at bottom, subservient only to the pro- 

 tection of the body as a whole. 



Thus there is a uniformity in the way the princi- 

 ple of division of labor is carried out in the econo- 

 my of animal lite. 



Union College, Schenectady, N. Y. 



PARIS LETTER. 

 While MM. Krebs and Renard are pursuing their 

 interesting researches concerning a;rial navigation, 

 and the manner of obtaining that much desired re- 

 sult, the method by which balloons are to be steered 

 in any given direction, other investigators are grap- 

 pling with the no less interesting problem of sub- 

 marine navigation, and trying to build boats that 

 can swim in mid-water, rise to the surface, or sink 

 to the bottom, at will, and be propelled in any di- 

 rection. The problem is not' an easy one to deal 

 with, but when it shall be solved, many interesting 

 questions will receive also a rapid answer. Subma- 

 rine navigation is very important from the military 

 standpoint, but the zoological results will certainly 

 prove more interesting to our readers, as they do to 

 ourselves, than the fact that a new man-destrover 



has been invented. With submarine boats, many 

 problems will be solved, concerning the life and 

 habits of marine animals, the depth of waves, the 

 temperature and currents of the .sea, etc. The ques- 

 tion of submarine navigation has been progressing 

 much of late in France. The first submarine boat 

 wliich has been built originated in 1863 ; it was called 

 the Plonr/eur (the Diver) and has been built by Ad- 

 miral Bourgeois. A small model of this boat is de- 

 posited in the marine museum, in the Paris Louvre. 

 The Plongeur was in shape like a cigar, and built in 

 sheet-iron. A screw-propeller was put in motion by 

 a compressed-air machine, and the compressed air, 

 besides furnishing the area with the necessary oxy- 

 gen for respiration, was used for raising the boat to 

 the surface. At the bottom of the boat were a series 

 of reservoirs, which could be filled with water or air 

 at will, to oblige the boat to sink or rise according 

 to circumstances. The boat was not able to remain 

 at any length of time at any intermediary level, 

 and this was its principal fault. After this Dupuy 

 de Lome was happy enough to secure this much de- 

 sired result; he obtained a boat able to remain at 

 any desired level under the surface. M. Zede, his 

 pupil in submarine navigation, obtained through 

 hard work more satisfactory results ; and his boat 

 w hich has just been achieved, the Gymnote, is a very- 

 good one. It was begun in 1886 and is now com- 

 pleted. The motor is no more a compressed-air 

 machine, but an electric storage battery. The Oym- 

 note has the same shape as the Plongeur but is built 

 of steel, and is much smaller (iS meters long, and 

 1.80 m. in breadth, instead of 42 x 6 meters). Its 

 motor consists of a battery of cells, invented by M. 

 Krebs, and the cells are used to set dynamo-ma- 

 chines in action; they develop 55 horse power, and 

 the motor is very light. The speed is of 9 or 10 

 knots per hour. The military uses of this boat are 

 not yet exactly ascertained; it will be used for tor- 

 pedoes, but whether mobile, or not, it has not been 

 decided; experiments will answer to this question. 

 At all events this sort of boat will be used only for 

 the defense of ports and coasts, and its services 

 would not be available in the open sea. 



Another boat has been recently devised by M. 

 Goubet, a civil engineer of Paris, and has been sub- 

 mitted to the test of e-xperiment at Cherbourg. This 

 boat is 6 meters long, and i m. and a half wide. It 

 is entirely made of bronze, and its weight is 10,000 

 kilogrammes. It is also cigar-shaped, and at the 

 roof, a small observatory, with thick glass, pro- 

 trudes to allow of observation, whether under or 

 above the level of the sea. Two men coinpo.se the 

 crew. The boat has been down to 13 meters depth 

 very easily, and has well supported the tremendous 

 pressure of 260,000 kilogrammes e.\erted on its sur- 

 face at this depth. The uses it will be put to in 

 naval war, will be deterinined later, after new exper- 

 iments on the subject; the time during which the 

 crew may remain in the boat without experiencing 

 any inconvenience is eight hours. 



The projected experiment of Dr. Tanner — if not 

 a hoax — who proposes to submit himself to a vol- 

 untary hibernation, such as that which is common 

 during the cold .season among a number of aniinals, 

 has created some comment on the general topic of 

 human hibernation, and a writer of the Revue Svien- 

 tijiqne has recalled, in a short paper the main facts 

 connected with this subject. Those which concern 

 animals are sufficiently well known, and it. would 

 be useless to recall them; but those concerning men 

 are generally less known of the public. 



It is in India that human hibernation seems to be 

 most frequently observed, and many travellers have 

 written curious accounts of the feats accomplished 

 by different fakirs. One of the most reliable is the 

 account given by Capt. Wade and Gen. Ventura. 



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