Novkmbi;r, 1911. 



KNOWLEDGE. 



451 



postei-ior limbs, and injects the instantaneously paiulvsiiiL; 

 venom from the forceps. It sometimes kills thrc:e or finii' 

 without stoppini,' to eat. The dead liodies are masticated, lint 

 only the soft parts arc ingested. 



.ASS()CL\TI()NS.— Professor Ch.irles Chih(.n. of Canter- 

 bury College, New Zealand, has recently described some 

 interesting examples of what he calls "commensalism," — a 

 term which should, we think, be restricted to cases of 

 mutually beneficial external partnership. One of these cases 

 is th.at of a crab iParaiitithrax loiigipcs). which seems to be 

 alnn)st invariably accompanied by specimens of Balaiiiis 

 dccorus growing on its carapace, the cirripedes being in some 

 cases so large and numerous that they exceed in size the body 

 of the crab itself. Here we have to deal with an " epizoic 

 association." probably quite unimportant in its initial stages, 

 but gradually, as the cirripedes grew, becoming inimical to 

 the welfare of the bearer. 



The second case is that of a hermit-crab ilinpagurus 

 steu'arti). which has a straight abdomen, and inhabits tubes 

 formed bya Millcpora, or, in other cases,"a massive calcareous 

 I'oKvoon. which is very much larger than the crab, so nmch so 

 that it seems doubtful if the crab can drag its large, solid 

 dwelling-place about with it." Professor Benham has suggested 

 that the cylindrical cavity inhabited by the crab may be due 

 to the decay of a branch of seaweed around which the Millepore 

 or the Polyzoon grew. 



Some of the associations that have been reported from time 

 to time are very remarkable, and Professor Chilton refers to 

 Dr. .Mcock's description of the intimate commensalism between 

 an Indian Ocean hermit-crab, (Pagtiristcs typica), and a 

 sea-anemone of the genus Mainillifcra. The sea-anemone 

 settles on the hinder part of the young hermit-crab's tail, and 

 the two animals grow up together in such a w-ay that the 

 spreading anemones " form a blanket which the hermit-crab 

 can either draw completely forward o\cr its head or throw 

 half back as it pleases." 



BEE DLSE.'XSE.— We notice that Dr. H. B. Fantham and 

 Dr. Annie Porter have found bees and combs, from 

 Cambridgeshire and Hertfordshire, infected with the Micro- 

 sporidian (Noscnia apis) which was found by Zander in 

 Bavarian bees. This parasitic Protozoiin belongs to the same 

 genus as the organism which causes pebrine or silkworm 

 disease, and the authors think that it has been responsible for 

 a good deal of the " bee disea.se " of recent years. It causes 

 a sort of dry dysentery. Infection occurs by means of spores, 

 as was experimentally proved. Unluckily, the only certain 

 destructive agent is fire. It nmst be noted that according to 

 Dr. Maiden there is also a bacillary infection in bees, the 

 parasite being called BacillKS pest i form is apis. 



A TELL-TALE C.4RTILAGE. — In the inner upper corner 

 of our eye there is a minute half-moon-shaped fold, the Plica 

 sail iliiimris. .m item in that museuin of relics of past .history 



which we carry about with ns in our body. For it corresponds 

 to the third eyelid I in whole or in [)artl which is well-developed 

 in mo^t mauuuals and helps to clean the eye. It is vestigial 

 nut (inl\- in Man, but in Monkeys and in Cetaceans. Its 

 practic.d absence in the Cetaceans is compensated for by the 

 continuous washing of the eye with wati-i. and in the other 

 cases to some extent by the frequent inovetnents of the upper 

 eyelid. It seems to be a very old structure this third e\'elid, 

 for it is the " nictitating membrane" that is flicked across the 

 e\e of birds, and it is also represented in most Reptiles. 

 What prouipted these remarks, however, was not the Plica 

 seinihinans itself, but a minute cartilage which it sometimes 

 includes even in Man. This is a great rarity in white races, 

 occurring in less than one per cent. Giacomini found it in 

 four cases out of five hundred and forty-eight whites. But 

 he found it twelve times in sixteen coloured people, and 

 Adachi found it five times in twenty-five Japanese. Dr. Paul 

 Bartels has recently examined twenty-five South African natives 

 (eight Hereros and seventeen Hottentots) and has found the 

 cartilage in twelve. Now as the cartilage is found in all .'Vpes 

 and Monkeys it seems fair to say that, so far as the cartilage 

 of the third eyelid vestige goes, some races are more thero- 

 morphic than others. — more conservative of their historical 

 relics. 



YE.ASTS OF INSECTS. — We are continually impressed 

 with the inter-relatedness of organisms in the web of life, and 

 an interesting fresh case has been recently reported by Dr. 

 Karel Sulc. He has been studying accumulations of reserve 

 material which occur in ."Xphides, Scale-insects, Coccids, and 

 related insects, and finds circumstantial evidence of a wide- 

 spread symbiosis between the insects and various specific 

 yeasts of the Saccharomyces type, which seem to work out 

 changes in the stores within the body. 



SENSE OF DIRECTION IN THE BLIND.— It is well 

 known that most blind people become aware when they are 

 approaching an object or even when an object is very quietly 

 brought near them. There has been a great deal of specula- 

 tion and not a little experimenting concerning this sense, which 

 has received many names — sense of obtacles, facial perception, 

 sense of direction, feeling at a distance, and so on. The 

 accounts that the blind themselves give of their perception 

 are very contradictory. Some investigators have regarded 

 the sense as a fine facial touch-sense, others as due to heat- 

 waves, others as sensitiveness to changes of pressure in the 

 air, others as auditory. Recent experiments of an ingenious 

 kind made at the Institution for the Blind in Paris, ha\e led 

 M. Truschel to the conclusion that the perception is of an 

 auditory nature and due to the fact that the object reflects 

 and alters surrounding sounds. To the objection that a deaf- 

 mute has been reported as showing the power, he answers 

 that those deaf to music and speech are often sensitive to 

 very feeble noises. 



By using ball-bearing rollers 

 the force of gra\it>' may 

 be utilized for conveying 

 bricks a long distance for 

 loading on cars as shown 

 in the accompanying illustra- 

 tion (Figure 1). No hand 

 laboiu' whatever is required, 

 and no power is utilized 

 with this carrier system, 

 which takes advantage of 

 gra\'ity to do the work. 

 The bricks are simply placed 

 on the carrier within the 

 kiln and they are started 

 on their \\ av to the car. 



AJADING BRICKS V>\ (,RAVITY, 

 Bv FK.\NK C. I'ERKINS. 



where they are loaded by 

 another operator and placed 

 in position for shipment. 

 The friction is so small 

 on the ball bearings of the 

 rollers that only a very 

 slight incline is necessary 

 on the conveyor system to 

 automatically carry the bricks 

 long distances, and the 

 \arions sections of the con- 

 \'eyor may be shifted as 

 desired, the material to be 

 liiaded taking single and 

 double curves when necessary 

 without difficultx'. 



