226 THE MICKOSCOPE. [November, 



109. H'^/iv do pla7its take double staining? Is there such 

 thi7ig as triple staining? 



Certain growing or active cells or part of cells absorb staius 

 more readily than older or harder portions. Triple or even quad- 

 ruple staining is possible. Aniline blue and magenta would stain 

 a growing stem about like this : Pith and hairs, pale magenta ; 

 cellular tissue and liber cells, deep magenta ; cuticle parenchyma, 

 pale blue ; pitted vessels, blue ; spiral vessels, cambium, laticifer- 

 ous vessels and epidermis, deep blue. 



1 10. Does thejiy zvalk o?i the ceiling by the aid- of suction or 

 exudation a?id cohesion ? 



Flies walk by suction, aided h\ their claws, on rough surfaces. 

 Many insects with well-developed claws can also walk on a rough 

 ceiling. 



111. About how many genera of diato7ns are there ? 

 There are more than 100 o^enera of diatoms. 



113. Ca7i the same bee sti7ig tzvice ? 



A bee can sting a soft-bodied insect or larva repeatedly, but 

 the tougher, human skin usually holds the sting by the barbs, so 

 the bee loses its weapon. 



113. What is the explanatio7i of the nzunerous spider webs 

 appearing at times rather sudde7ily i7t the ?7iorni7ig ? 



These webs are usually the work of recently hatched spiders. 

 Delicate webs may be unnoticed during the day and become 

 plainly visible after dew or dust has settled on them. 



114. Are the facets i7i the eyes of i7isects co7ivex or concave ? 



These facets are convex and, acting like convex lenses, form a 

 magnified image of near objects. 



115. Which way do the hexago7ial cells i7i the oyster-shell 

 grow ? 



Oyster shells grow by successive layers deposited on the inside 

 and extending beyond the edges of the older shell, forming lines 

 of calcified cells parallel with the external surface. 



116. Do several varieties of fi7igi affecct the sa?77e pla7it. or 

 does each plant have its specia^l fungus ? 



Parasitic fungi are either the cause or the accompaniment of 

 disease, and the more highly the plant is cultivated the more deli- 

 cate it becomes and more susceptible to disease. Plants are 

 usually affected by one variety of fungus, but at times may be- 

 come the host of several varieties. 



