142 



♦ KNOWLEDGE * 



[Feb. 20, 1885. 



brain, or tlie two brains:, may not each be trained to dis- 

 charge this duty ; for the disease of either would no longer 

 destroy or seriou.sly impair the power of sight. 



The next point to be considered is that of gesture. It is 

 maiutaiced by Brown-Sequard that the left side of the 

 brain chiefly controls the gestures, and this for the simple 

 reason that the left side of the brain guides chiefly the 

 movements of the right side of the body, and it is chiefly 

 with the right arm that gestures are made. But it also 

 appears likely, from certain pathological fact.=!, that even 

 the motion of the left arm, so tar as gestures are concerned, 

 depends on the action of the left side of the brain ; for it 

 is found that patients who have the left side of the brain 

 diseased commonly lose the faculty of making appropriate 

 gestures with either the right or the left arm. It has, 

 however, happened in a few cases that the disease of the 

 right side of the brain has led to a los-s of the power of 

 making gestures. It need hardly be remarked that this 

 '■xception no more opposes itself to the general theory of 

 the duality of the brain than does the fact that a certain 

 proportion of persons are left-handed, or one may say left- 

 aided. 



There is a dirficulty in determining how far writing 

 depends on the lefc side of the brain, because disease 

 of that fride is not uncommonly acoe.nijianied by 

 paralysis of the right arm and hand, and in such cases 

 we cannot determine whether the power of writing is 

 lost on account of a real loss of memory of the relation 

 between written symbols and the ideas they express, or simply 

 through the effects of paralysis. However, it very seldom 

 happens that paralysed patients have lost altogether the 

 use of the fingers and are unable to make the least sign. 

 In fact, it is found that in many cases they can imitate 

 writing placed before them (oftener if the handwriting 

 resembles their own) while they are unable from memory 

 to write anything, or, at all events, to express ideas by 

 writing. The disease is called agrap/iia. In many-patients 

 suffering from this disease the right arm is perfectly free 

 from any sign of paralysis, but a portion of the left side of 

 the brain has been diseased. It woultl appear, therefore, 

 that written language, like spoken langu;igp, depends on 

 the left side of the brain. 



It is also known that the power of reasoning depends on 

 the left side of the brain more than on the right. In cases 

 of insanity the left side of the brain has more frequently 

 been found to be diseased than the right side. 

 (To he continued.) 



ON TERMITES. 

 By Surgeon-Generai, R. F. Hutcuinson, M.D. 



{Continued from p. 104.) 



TERMITES have the same family arrangements and the 

 same stages of development as their darker brethren, 

 and share with them the crowning wonder of a wonderful 

 life in the terminal swarm of the male and female winged 

 insects. That of the ant is an unnoticed afl'air ; that of the 

 termite upsets the whole household by night and the 

 whole neighbourhood by day. 



They never swarm out here until about twenty-four hours 

 .•ifterrain, and never, except during the rainy months — June 

 to October. The " secret of water " is as necessary for the 

 last transformation scene of the termite as for rousing the 

 frog from his estivation. In the case of the former, it is 

 more diflicult to understand the close connection between 

 moisture and termite perfection, because the condition 

 brings with it no alimentary advantage. I believe the 



secret lies in the fact that moisture is essentially necessary 

 to the unfolding of their large and delicate expanse of wing, 

 for the process would be embarrassed, if not arrested, by 

 the fiery blast of the hot wind which precedes the rains. 



But, then, what is the use of the wings? It is certain 

 that fertilisation does not take place during flight, and, 

 from the very early wing-dropping, it is equally certain 

 that these delicate organs are not necessary for the pur- 

 pose. What, then, the necessity of the swarm ? I believe 

 it to be a provision of nature for lessening the species by 

 bringing it into contact with the host of devourers ready to 

 hasten to the feast either by day or night. 



If these were not available to lessen the swarms, and its 

 units returned to the earth whence they came, then the 

 soil would very soon be dominated by these ruthless 

 devourers. My remarks have hitherto only applied to 

 their ravaging inorganic matter. Many a tree do they kill 

 by barking ; many a choice garden-plant, roses especially, 

 do they similarly destroy ; while their havoc among vege- 

 tables, especially potatoes, is very serious ; nor do straw- 

 berries escape their notice. 



Let us now try and watch a swarm ah inilvi, and in this 

 out.side mud house-wall we have an opportunity. While 

 casually passing our eyes across it, we note the sudden 

 appearance of a pinhole, and out of it the inquisitive 

 antennaj of a worker, exploring in every direction. Know- 

 ing what is going to happen, we closely watch, and presently 

 the antennas are followed by the body of the worker, who 

 proceeds to examine all round the hole, and is joined in 

 the survey by a second worker. Apparently, both are dis- 

 satisfied, and begin enlarging the hole with their mandibles. 

 While so engaged, the brownish- black mandibles of a 

 perfect insect appear, and, with a mighty effort, it squeezes 

 out of the hole, stops to breathe a moment, and then takes 

 flight. More workers pass out of the hole, and great 

 excitement prevails as, one by one, the perfected insects 

 emerge. The same scene is being enacted at other openings 

 which have suddenly appeared in the wall ; and now it is 

 covered with fluttering termites and excited workers. 



As you gaze you are enveloped in a cloud of flyers, and 

 can see that it is rising high into the air. Watch, and you 

 will soon see that kites, crows, king crows, jays, mynas, 

 sparrows — nay, the whole feathered race — are flocking to 

 the feast, and that below, the poultry-yard, led by the 

 guinea-fowls, are similarly occupied. 



Note how laboriously the kites feed : each termite is 

 seized by the claws and then conveyed to the beak : the 

 other birds charge ruthlessly into the swarm with open 

 beaks, and seize all they can. If this flight occurs towards 

 dusk, you will find bats, even the frugivorous flying-foxes, 

 and little owls joining in the revel. 



After watching the flight for about twenty minutes, you 

 will find that the survivors have alighted, and are now 

 chasing one another in amorous pairs. This is the period 

 of fertilisation. 



Turn we now for a moment to the wall whence the swarm 

 issued, and we shall find that the workers have carefully 

 plastered up all the holes of exit, and the recent scene of 

 busy activity is now bare and deserted. 



Resuming our inspection of the perfect insects, we shall 

 find to our amazement that they, too, have disappeared, 

 and that naught remains of the great rush into life ai^d 

 activity but the disjected wings which thickly strew the 

 ground. The disappearance in a room is still more marvel- 

 lous, for within its walls you can imagine fewer places for 

 retreat or concealment ; yet, under your very nose the 

 survivors of the swarm escape, and you can't say how. 



The sudden appearance of a swarm at dinner-time, 

 especially it there are lights on the table (as in the 



