56 



KNOWLEDGE 



[Mabch 1, 1894. 



home there, as well as a Uttle solitary bee ; so that in this 

 one spot there were eddences, in one way or other, of the 

 presence of no less than half a dozen different sorts of 

 creatures, an association in large degree accidental, but 

 still full of perplexing complications to anyone who was 

 not familiar with the habits of the different itiiembers. 



It is not always abandoned burrows that are thus 

 appropriated by indolent excavators ; sometimes burrows 

 that have just been made by one species will be captured 

 by another, though it usually requires some diligence and 

 perseverance, as well as courage, to retain possession of a 

 site thus surreptitiously gained. For example, a Trypo.n/lon 

 was found frequenting the holes in a post which had been 

 pre-occupied by one of the solitary wasps of the genus 

 Odynerus. The little black invader had begun to lay in a 

 stock of provisions in the shape of a small round ball 

 containing about fifty aphides. The legitimate proprietor 

 of the buiTow. on her return, seized the pellet, and, flving 

 out with it held between her legs, dropped it about a "fool 

 away from the entrance. The Tnjpo.vjihm again picked up 

 her luggage and replaced it, but on the return of the wasp 

 it was again turned out, and this continued several times, 

 till, the wasp being absent longer than usual, the Tn/po.ri/hm 

 had time not only to replace the obnoxious parcel, but also 

 to cement up the entrance of the burrow. The Och/nrnis 

 was thus checkmated, for though she repeatedly returned 

 to the spot, she made no attempt to force an entrance 

 through the barricade, but finally departed in search of 

 more peaceful quarters. 



We must now pass to the second of our groups of 

 stingers, which comprises such other hvmenopterous 

 insects as are able to prick the skin, but not to make a 

 painful wound, since no poison accompanies the puncture, 

 and the effects are of the most transient description. 

 I nder this head come only certain members of the great 

 group of ichneumon flies, and we may therefore dismiss 

 them with but a brief notice. As before, it is only the 

 females that possess the boring implement. Its structure 

 is, in general plan, similar to that of the sting of bees and 

 wasps, but there is no poison gland. There are two side 

 pieces which act as a sheath, and a central barbed borer. 

 The purpose of the instrument is, in general, to pierce the 

 bodies of insects so that eggs may be inserted beneath the 

 skui, for the ichneumon flies are, in their early stages, 

 internal parasites, and their larvre, which are fat "maggots, 

 devour the contents of the bodies of their hosts, in such a 

 way, however, that no vital parts are touched till there 

 ceases to be any necessity to prolong the life of the doomed 

 victim. 



The boring weapon is usually more or less visible outside 

 the body, and is sometimes extremely long. A very Ion" 

 ovipositor usually implies that the host lives in rather 

 inaccessible places, which the ichneumon itself cannot 

 reach, as is the case, for example, with those insects that 

 mhabit tunnels which they have excavated in the trunks of 

 trees. In such cases the ovipositor can be passed in at 

 openmgs which are too small to admit the bodv of the 

 ichneumon itself, or it may even make an entrance for 

 Itself by being worked through the wood. The prey can 

 thus be reached, and the eggs deposited in the proper 

 situation. Even in English species this boring and e"g- 

 laying machine may be much longer than the body; one 

 13 now before me in which the body is half an inch long, 

 while the ovipositor extends for nearly an inch beyond 

 this. But from Japan comes the record of a species of "Bra- 

 conidK which has the body three-quarters of an inch long, 

 while the boring weapon attams the extraordinary length 

 of SIX and three-quarter inches ! The ichneumons with 

 long ovipositors arc not the ones to use them on human 



kind ; the instrument is too flexible and too blunt to be 

 used with any effect on the human skin. But some of the 

 larger kinds that have very short ovipositors can give a 

 sharp prick, which causes one to drop them immediately 

 under the impression that a real sting has been received". 

 However, the sensation is only momentary, and no lasting 

 effect is produced. 



(To be continued.) 



THE SACRED WATER OF MECCA. 



By C. A. Mitchell, B.A.Oxon. 



THEOUGH the kindness of Lady Burton, I have 

 been enabled to make an analysis of some of the 

 water which the late Sir Richard Burton, 

 disguised as a pilgrim dervish, brought back from 

 Mecca in 1853. 

 The Zem-Zem Well, according to tradition, is the Well 

 of Hagar, and is used for no other purpose than drinking 

 and religious ablution. Each pilgrim to Mecca is anxious 

 to drink and bathe in the water, but as there is not 

 sufficient for all, the following device is adopted : — One 

 Arab, standing on the wall of the well, draws the water up 

 and pours it over the pilgrims as, stripped to the waist, 

 they advance in turn. As it pours over him each drinks 

 what he can, and the remainder runs down, soaking 

 through the loin-cloth, back into the well, to be used again 

 on succeeding pilgrims. If this practice has been continued 

 day after day and year after year, it is not surprising to 

 find that the water is very rich in chlorides, and that it con- 

 tains a large quantity of solid matter in solution. 



Sir Eichard Burton described the water as extremely 

 nauseous in its taste, and resembling a strong dose of 

 Epsom salts. This observation is borne out by the 

 analysis, which shows that magnesium sulphate (Epsom 

 salts) is an important constituent. Its use is said to 

 produce boils and other unpleasant results, and should the 

 well happen to become infected with cholera germs, a 

 far-reaching epidemic is the probable result. Large 

 quantities of the water are exported from Mecca to other 

 Mahommedan countries, and those who drink it are 

 believed to acquire the facility of speedily learning Arabic. 



The sample analyzed was contained in two small tin 

 bottles which were hermetically sealed, and which had 

 remained untouched since they were brought from Mecca. 

 Together they contained about half a pint of the water. 

 On opening them there was a slight evolution of gas, and 

 the water within was found to contain a quantity of beau- 

 tiful silky crystals in suspension, and a few earthy particles 

 settled at the bottom. On examination these minute crystals 

 proved to be a comjjound of tin, which had been formed 

 by the long-continued action of the water on the interior 

 of the tin bottles. These foreign matters being filtered off, 

 there was left a clear colourless liquid with a slight smell, 

 which was more perceptible on warming. No trace of tin 

 could be found dissolved in the water. 



In judging as to the fitness of a water for ordinary use, 

 the chief points to be determined are the amount of 

 solid matter left on evaporating a certain definite quantity, 

 the amount of chlorine present in solution, the liardness, 

 and the amount of free ammonia and ammonia in com- 

 bination with animal or vegetable matter (i.e., albuminoid 

 ammonia). 



As a general rule, waters which contain less than 

 forty grains per gallon of sohd matter in solution are not 

 condemned if the other points are satisfactory. The 

 method of determining this solid residue is to evaporate a 

 definite quantity of the water in a platinum dish, and to 



