68 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Organs of Sense in Spiders.* — F. Dahl gives a brief account of 

 the zoological points of some recent observations on the psychological 

 processes in spiders. Sight is imperfect, tlierc being no power of 

 accommodation. A very short distance suffices to make a spider 

 mistake for a fly any small moving object, e. g. a pellet of paper. 

 The sense of touch is, by way of compensation, highly developed. 

 The spider, taking its stand in the centre, can by touch tell in what 

 precise radius a foreign body strikes against its web. Smell and 

 hearing are well developed. Epeira patagiata can distinguish be- 

 tween different smells. 



In web-building several types regularly occur in the architectural 

 life of an individual spider. The first web is of a regular circular 

 shape with radiate strands, the animal taking up its dwelling in the 

 centre. The next web is composite, showing several simple webs of 

 the first type combined, and the abode or den of the spider is not in, 

 but near, the web i^roper — a signal-line connecting its place of con- 

 cealment with the centre of the web. 



Sjiiders avoid bees, wasps, and other dangerous insects, and Dahl 

 found that by dipping a given species of insect in turpentine (which 

 spiders dislike), a spider learnt to shun the species, as such, whether 

 anointed or not with the oil. 



Coxal Gland in the Phalangida.f — J- MacLeod describes coxal 

 glands in the Phalangida, which arc comparable to those lately seen 

 by Lankestcr in Limidus, scorpions, and tetrapneumonous spiders. 

 They are there made up of a number of glandular tubes which form 

 a closed system ; the cells that line the tubes are distinguished by 

 the fact that their external zone is strongly striated and well dif- 

 ferentiated, while their internal portion appears to be formed of 

 granular protoplasm, and to contain a nucleus ; and the organs of the 

 Phalangida have a similar structure. The presence of these glands 

 seems to the author to be an important aid in settling the vexed 

 question of the systematic position of these animals, and to favour 

 the view, now generally adopted, that they belong to the group of the 

 Arachnida ; the facts noted in his preceding paper point in the same 

 direction. 



Hermaphroditism of the Male of Trombidium.J— J. MacLeod 

 finds that the ca3cal sacs of the male gland of Tromhidium holoseriaim 

 contain ovules, situated among the mother-cells of the spermatozoa ; 

 they do not, however, complete their development or acquire the size 

 of the ripe ovules in the female, which were examined at the same 

 period of the year. 



f. Crustacea. 



Absolute Force of the Muscles of Invertebrates. § — In his 



second li essay on this subject F. Plateau deals with the flexor muscles 



* Zool. Anzeig., vii. (1884) pp. 591-5. 

 t Bull. Acad. R. Belg., liii. (188i) pp. 392-3 (1 fig.). 

 X Ibid., p. 393 (1 fig.). 

 § Ibid., pp. 450-74 (1 pi.). 



II For the first part (on Lamellibranch Molluscs) see this Journal, iv. (1884) 

 p. 212. 



