SCIENCE- G OS SIP. 



T 37 



The principal advantages claimed for the ozo- 

 type process are that (a) the image is visible 

 during the progress of printing, and when washed 

 is permanent ; {b) the picture, being produced 

 on the material, does not become reversed in the 

 operation ; (c) as the soluble chromium and other 



salts are thoroughly washed out before develop- 

 ment, the hands do not come in contact with any 

 deleterious solutions. 



Femleigh, St. James Road, Leicester, 

 September 1901. 



NOTES ON SPINNING ANIMALS. 



By H. Wallis Kew. 



(Concluded from page 71.) 



X. — Larvae of Weevils {continued). 



TN Phytobius, another genus of weevils, the little 

 -*- cocoon of Phytobius notula Schupp. has been 

 made the subject of research by Perris. He finds 

 that though parchment-like, and without meshes 

 when complete, the little structure is distinctly 

 comparable as regards manner of formation with 

 the cocoon of Hypera. The larva lives on the 

 water -pepper {Polygonum hydropiper) ; and its 

 body is covered with a slight layer of viscous 

 matter, coming from a nipple, which is here 

 situated at the extremity of the last segment, 

 below the anus. The cocoon, a little larger than a 

 grain of millet, is attached to a leaf. In making 

 it, the larva takes with its mandibles, from the 

 anal nipple, an almost imperceptible drop of the 

 viscous matter. This it attaches on one side of its 

 body, and, drawing it out into a thread, carries it 

 to the opposite side, so as to form an arch over the 

 body. It multiplies these arches always hy the 

 same process, crossing them in all directions ; and 

 at the end of about an hour it is enveloped with 

 a fine net, across which it can be seen for a long- 

 time stretching and probing the glutinous liquid, 

 with which it provides itself from time to time by 

 resorting to the nipple. It continues thus to work 

 until not a single aperture remains in the cocoon. 



In the case of Cioniis, a genus of weevils attached 

 to the mulleins and betonies, there is a statement 

 by Westwood ( 7 ) that the cocoon of the common 

 betony-weevil {Clonus scroplmlariae) is formed 

 with open meshes like that of Hypera. This is, 

 however, a mistake. These weevils, though not 

 immediate allies, have many characters in common 

 with Hypera, as well a,s with Phytobius. The 

 larvae, as in those genera, are free, and their 

 bodies are furnished with slimy matter, which is 

 here abundant, covering the whole body in a thick 

 layer. It comes from a nipple at the base of the 

 upper side of the anal segment. This nipple, 

 according to Perris ( 8 ), who has studied several 



(7) "Westwood, "Modern Classification of Inserts," i. (1839), 

 p. 343 ; and see Eye, ' ; British Beetles," 1866, pp. 194, 195. 



(8) Chapuis & Candeze, " Memoires de la Societe Boyale des 

 Sciences de Liege," viii. (1853), pp. 563-64, quoting Perris, 

 " Annales de la Societe Linneenne de Lyon," 1847-49, pp. 291- 

 302 ; Perris, 1851, he. ; and see Fowler, " British Coleoptera," v- 

 (1891), p. S23. 



species, is hidden in the tissues, but capable of 

 protrusion ; and the secretion, which is emitted 

 upon the preceding segment, gradually finds its 

 way to all parts of the body. The cocoons 

 which have been described by Reaumur, De 

 Geer, Perris, Osborne, and others ( 9 ), are not 

 of network, but of a continuous parchment- 

 like membrane. They are spherical, and are 

 attached to the plants on which the larvae feed. 

 De Geer compares that of Clonus scroplmlariae 

 to a little bladder, and remarks that, though thin, 

 it is strong, elastic, and a little transparent.. 

 Several writers ( l0 ) have remarked, further, that 

 it is strikingly like the seed-vessels of Scrophularia, 

 among which it is often placed. As regards the 

 manner in which these cocoons are made, Reaumur, 

 who observed a species on mullein, though aware 

 that the cocoon consisted of a membrane rather 

 than of threads, believed that he had seen in the 

 larva an oral spinneret ; but he was certainly 

 mistaken. De Geer, while thinking that some silk 

 might enter into the cocoon, beliered that it was 

 composed of the glutinous matter of the body of 

 the larva ; and this latter remark, it is now known, 

 well expresses the nature of the structure. Thus 

 the cocoon of Clonus can hardly be said to be 

 spun ; but parts of the larva's proceedings are so 

 like those of Hypera and Phytobius that we may 

 well take note of them. The result of the obser- 

 vations of Perris and others is that when the ; 

 larva is about to undergo its change to pupa, it 

 fixes itself to the plant, and, remaining motion- 

 less with the body contracted, it augments the 

 thickness of the layer of viscous matter which 

 invests it, and which then gradually dries around 

 the body, enclosing it completely. Then, detach- 

 ing itself from the layer, it finds itself free within 

 a cocoon. Subsequently, however, Perris says, the 

 larva consolidates the dwelling, from within, by 

 plastering it with the viscous matter, which it 

 takes from the anal nipple and spreads with the 



(9) Reaumur, " Memoires pour servir a l'Histoire des Insectes," 

 iii. (1737), pp. 31-33 ; De Geer, torn. cit. (1775), pp. 208-12 ; 

 Chapuis & Candeze, I.e. ; Perris, I.e. ; W. H. G., Hardwicke's 

 " Science-Gossip," 1876, pp. 17, 18 ; Osborne, I.e., and in Hard- 

 wicke"s "Science-Gossip," 1880, p. 209. 



(10) W. H. &., I.e.; Dimmock, "Standard Natural History," 

 ii. (1884), p. 342 ; Butler, " Knowledge," xvi. (1893), p. 227. 



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