1900] MICROSCOPICAL JOURNAL. 257 



gave a lantern demonstration on the structure of some 

 palaeozoic plants. 



Scale From Leaf of Lemon-tree. — The scale insects, 

 Coccidae,members of the order Hemiptera, sub-order Hom- 

 optera, belong to that division of the sub-order which is 

 distinguished by having only one joint on the tarsus. The 

 females are common on many plants, and are found both 

 on leaves and bark. They appear as small, brown, waxy, 

 convex lumps, more or less elliptical according to species. 

 If the brown case be lifted, one sees a small fleshy mass, 

 with eggs, and usually a cottony substance. The fleshy 

 mass is the female, which dies as soon as the eggs are 

 laid. The eggs hatch into a small, active larval insect 

 with eyes, legs, antennae, and a sucking mouth. After a 

 time these insects fix themselves to a leaf or the bark by 

 means of their sucker. If they are to become females they 

 excrete the waxy shell, throw off all legs and processes, 

 lay their eggs, and die. If they are to develope into males 

 they draw in their legs and become chrysalids, with a 

 process on each side containing the future wings. The 

 adult males are seldom seen. The male and larva are 

 figured in Miss Ormerod's book. A friend of mine is now 

 trying by an ingenious contrivance to obtain specimens 

 of the males and larvae. He has run the branch of arose 

 tree, not cut off, into a lamp chimney, and packed the 

 ends with cotton wool. He thinks that when the scale 

 eggs on the branch hatch out he will find the larvae inside 

 the glass. The second slide shows a scale in which a para- 

 site, probably an ichneumon fly, has laid its eggs, and the 

 grub has hatched and eaten all the scale eggs. The grub 

 is shown lying by the side of the scale. The scales thus 

 attacked are usually of a lighter color than the rest. 



Sheep-tick Imago. — A tick is a degenerate fly that has 

 lost its wings. The sheep-tick passes the larval state in- 

 side the body of the mother. The pupae may be found in 

 little brown shiny cases about three millimetres in diam- 



