Aug. 15, 1884.] 



• KNOWLEDGE ♦ 



125 



AN ILLUSTRATED 



MAGAZINE OF SCIENCE 



LONDON: FRIDAY, AUG. 15, 1884. 



Contents of Xo. 146. 



Pleasant Hours with the Micro- 

 scope. (lUui.) By Heiiry J. 

 Slack, F.O.S., F.R.Vr.S 125 



The Capture Theory of Comets. By 

 Eichuril A. Proctor 128 



Chemistry of Cookery. XL. By 



W. M. AVilliams 128 



Optical Recreations. (lilies.) By 

 F.H.A.S 129 



The History of a Lightning Flash. 

 ByW. Slingo 131 



The Earth's Shape and Motions. 

 (Illus.) By Hichard A. Pn.ctor. 133 



The Entomology of a Pond. (/««».) 

 By E. A. Butler 134 



riei 



Zodiacal Maps. By li. A. Proctor 13ti 

 Other Worlds than Ours. By M. 

 de Fontenelle. AVith Notes by 



Bichard A. Proilor 136 



Remarkable Storms in Belgium 138 



International Health Exhibition. 



XII J38 



The Grecly Eipedition 140 



Reviews 141 



Editorial Gossip 141 



The Face of the Sky. By F.E.A.S. 142 



Miscellanea 143 



Correspondence 143 



Our Mathematical Coltinm 145 



Our Chess Column 146 



PLEASANT HOURS WITH THE 

 MICROSCOPE. 



By Henry J. Slack, F.G.S., F.R.M.S. 



THERE is a remarkable group of small insects interest- 

 in;,' to the microscopist on account of their beauty 

 and their strangeness, and interesting, also, in a bad sense, 

 to the agriculturist and the gardener on account of their 

 destructive habits. They belong to the Order Thy sanoptera, 

 or Fringe-wings, characterised by " four wings, alike, 

 narrow, membranous, neither folded nor reticulated, with 

 long cilia>, laid horizontally along the back when at rest." 

 Westwood, in his " Introduction to the Modern Classifica- 

 tion of Insects," cites Haliday, the first important English 

 observer,* and, in the main, agrees with his description of the 

 mouth parts of these creatures, which, he says, " though con- 

 structed " in the mandibulated and palpigerous form, unite 

 into a short conical sucker, which does not extend beyond the 

 anterior coxse." Curtis, in " Farm Insects," specially 

 describes the species which injures corn (T. cerealium), 

 and speaks of the trophi or mouth-parts uniting to form a 

 short beak. Duncan, in his pretty book, " Transforma- 

 tions of Insects," founded upon Emile Blanchard, speaks of 

 this species " nibhUngih^ protecting envelopes of the grain" 

 — a thing they could only do if they had mandibles con- 

 structed for biting, which is not the case. Westwood, 

 although not detecting the principal feeding organ of these 

 insects, judiciously said : " It appears doubtful whether the 

 action, even of the maxilla?, can be transverse, or whether 

 the insect can be said to bite its food." 



The kind common in greenhouses is rather more than 

 one-fifteenth of an inch long in its adult stage, exclusive of 

 its antennas. Its appearance, when considerably magnified, 

 is shown in Fig. 1. To the naked eye, the full-grown 

 specimen looks black, with white gauzy wings: but when 

 mounted in Canada balsam, and seen with transmitted 

 light, the colours are shades of brown, some much lighter 

 than others, which may be a matter of age. Dark -ground 

 illumination, and a magnification of about 50 linear, makes 



* " Entomological Magazine," Vols. III. and IV. 



them objects of great beauty. Each segment of the little 

 creature is decorated with an elegant network pattern. The 

 antenna; are foimed of segments like slender vases, the foot 

 of one in the cup of another, and terminate like the top 

 joints of a fii<hing-rod, the tip being exceedingly fine. 

 Westwood says the number of joints varies from five to 

 nine, in consequence of the terminal joints being more or 

 less firmly soldered together. Fig. 5 shows the appear- 

 ance of this organ highly magnified. The eyes are large 

 aud coarsely graiailatcd, and there are ordinarily three 

 ocelli. 



Fis. 1. 



Fi^'. 2, 



V\ir. 3. 



Fig. 4. 



Descbiptiox of Figures. 



Fig. 



Fig. 1. — Greenhouse Thrip, highly magnified. 



Fig. 2. — Rostrum. This is generally seen straight. The sketch is 

 from one slightly curved , showing it is flexible. 



Fig. 3. — Outline of maxillary palp. 



Fig. 4. — Outline of labial palp. 



Fig. 5. — Outline of antenna, drawn on a large scale, as a smaller 

 one would not show the proportion the fine tip bears to the stouter 

 parts. 



Curtis says : " Every one must he acquainted with a 

 little black insect, which alights on the face in hot weather, 

 causing an intolerable irritation with its bladder-tipt feet, 

 throwing up its head and twisting about its tail to expand 

 or close its beautifully-fringed wings." The writer has not 

 experienced this annoyance, which may be perpetrated by 

 T. cerealium. The greenhouse sort, though common on 



