OAK-APPLE. 



OAK BARK. 



Spanish oak (Quercus falcata, of Michaux) 

 me bark of this species is somewhat rough 

 and light-coloured. The leaves are deeply an 

 obtusely sinuated, and end in several acute 

 bristly points : the foot-stalks are pretty long 

 The timber is generally worm-eaten, or rotten 

 at heart ; but the bark is preferred to ail othe 

 for tanning, and is much dearer. 



Live ox k (Quercus virens). This species is ex>n 

 fined to Georgia, South Carolina, and Florida 

 The tree is of uncommon magnitude, and sin 

 gularly beautiful. The moss hangs in lengths 

 of several yards from the large branches of the 

 old trees, and waving with the wind, gives the 

 tree a venerable appearance. The wood is 

 proverbial for its durability, when cut at a 

 proper season, and is much used for ship 

 timber. See ACORNS, Dnr ROT, and PLANTA 



TIOVS. 



OAK-APPLE. This is not to be confounded 

 with those beautiful little excrescences so com- 

 mon upon the underside of the leaves of the 

 oak, and known by the name of galls and 

 spangles; they are the nidi of different species 

 of Cynips, produced by the puncture of the ovi 

 positor of the female, upon the different parts 

 where they are found. The oak-apple is also 

 formed by the puncture of a cynips, upon the 

 ( (J. jifihmrnlnta. It rises rapidly, is 

 usually spheroidal, in size about 1 to 2 inches 

 in diameter. Its texture is spongy. It has 

 some resemblance to the fiedri/nnr of the Eg- 

 lantine, but is not so rough and fibrous on the 

 surface. The oak-apples are very astringent, 

 containing tannic acid, and may be used in 

 dyeing, making ink, and staining. 



The largest galls or oak-apples, found in the 

 United States, grow on the leaves of the red 

 oak. They are round and smooth, and measure 

 from H to 2 inches in diameter. This kind of 

 gall is green and somewhat pulpy at first, but, 

 when ripe, it consists of a thin and brittle shell, 

 of a dirty drab colour, enclosing a quantity of 

 brown spongy matter, in the middle of which 

 is a woody kernel about as big as a pea. A 

 single grub lives in the kernel, becomes a 

 chrysalis in the autumn, when the oak-apple 

 falls from the tree, changes to a fly in the 

 spring, and makes its escape out of a small 

 round hole which it gnaws through the kernel 

 and shell. This, says Dr. Harris, is probably 

 the usual course, but I have known this gall- 

 fly to come out in October. The name of this 

 insect is Cynips conflucntus. Its head and thorax 

 are black, and rough with numerous little pits 

 and short hairs ; the hind-body is smooth, and 

 of a shining pitch colour; the legs are dull 

 brownish-red; and the fore-wings have a brown 

 spot near the middle of the outer edge. Its 

 body is nearly one-quarter of an inch long, and 

 its wings expand five-eighths of an inch. 



Clusters of three or four round and smooth 

 galls are often seen on the small twigs of the 

 white oak. They are nearly as large as bullets, 

 of a greenish colour on one side, and red on 

 the other. They approach in hardness to the 

 Aleppo galls, and perhaps might be put to the 

 same use. Each one is the nest of a single 

 insect, which turns to a fly and eats its way out 

 in June and July, having passed the winter as 

 a chrysalis, within the gall, lodged in a clay- 



coloured, egg-shaped case, about three-tw en- 

 tieths of an inch long, and with a brittle shell. 

 These little cases appear to be cocoons, but 

 are not made of silk or fibrous matter. Similar 

 cocoons are found within many other galls, and 

 I have some which were discovered under 

 stones, and were not contained in galls, but 

 produced gall-flies, the insects having left their 

 galls to finish their transformations in the 

 ground. The gall-fly of the white oak varies 

 in colour. Sometimes it closely resembles the 

 gall-fly of our oak-apple, differing from it only 

 in size, and in wanting the brownish spot and 

 dark-coloured veins on the fore-wings ; and 

 sometimes it isof adull brownish-yellow colour, 

 with a brown spot on the back. It is three- 

 twentieths of an inch long, and its wings ex- 

 pand three-tenths of an inch. It is the Di$lo- 

 lepis, or more properly Cynips oneratus of Dr. 

 Harris's Catalogue." 



Galls of the size and colour of grapes are 

 found on the leaves of some oaks. Each one 

 contains a grub, which finishes its transforma- 

 tions in June. The winged insect is the Cynips 

 mtbilifiennisjor cloudy-winged Cynips, so named 

 from the smoky cloud on the tips of its wings. 

 Excepting in this respect, it closely resembles 

 the dark-coloured variety of Cynips oneruws,and 

 very little exceeds it in size. 



One of our smallest gall-flies may be called 

 ( 'ij'iifn seminal or, or the sower. She lays a great 

 number of eggs in a ring-like cluster around 

 he small twigs of the white oak, and her punc- 

 ures are followed by the growth of a rough or 

 shaggy reddish gall, as large sometimes as a 

 walnut. When this is ripe, it is like brittle 

 sponge in texture, and contains numerous little 

 seed-like bodies, adhering by one end around 

 he sides of the central twig. These seeming 

 seeds have a thin and tough hull, of a yellowish 

 white colour; they are egg-shaped, pointed at 

 ne end, and are nearly one-eighth of an inch 

 ong. The gall-insects live singly, and undergo 

 heir transformations within these seeds ; after 

 which, in order to come out, they gnaw a small 

 lole in the hull, and then easily work their 

 way through the spongy ball wherein they are 

 odged. They are less than one-tenth of an 

 nch long, are almost black, or of the colour of 

 itch, highly polished, especially on the abdo- 

 men, and their mouth, antennae, and legs are 

 innamon-coloured. 



It has been observed that no tree in Europe 

 rields so many different kinds of galls as the 

 >ak. Those described are not all that are 

 ound on oaks in the United States, and they 

 eem to be sufficiently distinct from the galls 

 f European oaks. (Harris.) 

 OAK BARK. The cortical layer stripped from 

 tie oak tree. Oak bark is preferred to all other 

 ubstances in the tanning of leather, and in Eu- 

 ope brings a high price afterwards as a ma- 

 ure. The exhausted bark is used by gardeners 

 o produce a slight equable heat by its ferment- 

 tion, and may be advantageously used as a 

 lanure. The tan-balls, or muddy sediments 

 f tan-pits, are used for summer fuel. The 

 ark contains different quantities of tannic 

 cid, according as it is near to or distant from 

 he wood. Thus, the inner part, or libe*-, ac- 

 ording to Sir H. Davy's experiments, yields 

 3C 853 



