Jan. 1, 1886.] 



♦ KNOWLEDGE ♦ 



70 



of each race) tlie idea would be entertained that the 

 breath represented, or actually was, this second self; for 

 in sleep the breathing is scarce perceptible. Thus the 

 second self would be regarded as a spirit or breath, and 

 death would come to be regarded quite generally as 

 merely the prolonged, perhaps final, departure of the 

 spirit or breath from the other or bodily self. In 

 passing, too, we note that as the proper second self could 

 pass away and return to its companion body, so on occa- 

 sion other spirits good or bad might make that body their 

 temporary home, giving in one case " inspiration " in a 

 good sense (very definitely believed, I imagine, in old 

 times to be what its names implies, p-n in- breathing) and 

 in the other "possession " in an evil sense. 



These ideas would prevail long before any idea of asso- 

 ciating religious sentiments with them would bo enter- 

 tained, and still longer before the thought of assigning 

 what had been human spirits to natural objects or powers 

 would sugs-est itself even to the mere imagination. 



PLEASANT HOURS WITH A MICROSCdPE. 

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



MONGST the insects injurious to man, 

 aphides occupy a prominent place, and 

 no species are worse than the Cotton 

 Bugs, or American Blights. A visit to 

 an orchard assailed by these creatures 

 presents a curious aspect, the branches 

 and twigs glistening with white, 

 cottony - looking threads. Under this cover lie 

 multitudes of the insects. The slightest touch of the 

 finger squashes scores of them, and makes a nasty brown 

 stain. A hand-magnifier discloses the family parties. 

 Young and old are seen all higgledy-piggledy together in 

 what might be supposed a wretched condition of over- 

 crowding, but they are quite happy in their way. 



The microscopist should cut off some portions of the 

 afflicted twigs, and keep them for a few days in a box 

 with a glass lid. This allows their rapid multiplication 

 to be noticed ; but as the sap dries up, the bigger ones 

 soon die. The cottony stuff hinders observations of any 

 details, but it may be got rid of quickly by immersing 

 the insects in a drop of alcohol, and stroking them very 

 , gently with a fine needle or a bristle. The older ones are 

 so swollen out with the tree sap that a slight touch bursts 

 them, and it is then common to find a number of yonxg 

 ones escaping, some in a very forward condition, others in 

 an embryonic state. The adult viviparous females hnve 

 their bodies longer than their rostra, but the little ones 

 have their rostra considerably longer than their bodies. 

 The very early development of the sucking and piercing 

 mouth-organs is a striking fact in the life history of these 

 creatures. The rostra look quite out of proportion to 

 the rest of the new-comers, but it enables them to 

 practise their voracity with the least possible delay. In 

 the adults, as well as in the young, the piercing organs, 

 consisting of three fine tubular, sharp-pointed bristles, 

 are of great length — much longer than the bodies of 

 the full-grown creatures. This allows them to 

 swarm in clusters, one atop of another, and all suck- 

 ing away together. The young ones can move 

 actively, but they do not leave the family party in 

 which they are burn until the numbers render emigra- 

 tion indispensable, and tlieu they usually settle close to 



the old group, and do nothing but fill themselves with 

 the plant-juices and bring forth more young. The 

 antennoe are small, and the two top joints provided with 

 curious depressions, .surrounded with hairs, much like 

 that shown in the sketch of the antennie of the phylloxera 

 in Knowledge, August 28. (See Fig. 2.) 



The belief that antennaj may be organs of hearing is 

 strengthened by the occurrence of such formaticns. They 

 are hollow, with drum-like membranes .stretched over the 

 biittom, and may be sensitive to very slight sound-waves. 

 Neither hearing nor seeing, however, could be of much 

 iLse to a cottiin bug. The eyes are very small, and pro- 

 bably little used, as the vast majority of the insects pass 

 their lives huddled together where they are born, covered 

 with the cotton, and those that migrate from the family 

 heap, for the most part only move a quarter or half an 

 ineh further on the part of the plant that is attacked. 



The founder of a cotton-bug family is a viviparous 

 female, called a Queen aphis by Mr. Buckton. She is 

 larger than the one figured from him in the sketch Xo. 1, 

 and black. She is the product of an egg laid by an 

 impregnated female in a crevice of apple-bark, and, 

 acording to Buckton, she often dies before laying her egg, 

 in which case her body serves as a protecting cover. 



I'iSf. 1. 



Fig. 2. 



Fig. 3. 



Fig. 1 shows one of her adult children, the little streamers 

 being the cotton threads they exude. The young are 

 produced at a rapid rate, so that long twigs are covered 

 almost as soon as they are attacked, and only a sharp eye 

 detects the presence of the enemy before the trees are 

 infested with thousands, and conspicuously whitened with 

 the cotton down. Cold does not readily disagree with these 

 creatures. Mr. Buckton speaks of finding them plentiful 

 when the thermometer stood at 21° F.; and the writer 

 noticed the same thing on the ISth of November, when 

 the night temperature on the grass fell to '2-ir' F., and 

 must have been a few degrees lower where the aphides 

 were thriving in a bitter east wind. Violent rains are 

 much more destructive, and after two or three days of 

 downpour, several trees that had been thickly infested 

 were washed quite clean. When the trees are small, like 

 pyramids, bushes, &c., painting the affected parts with 

 strong .size is the best remedy ; but this is impracticable 

 with large old ones, and they perish under the attack. 

 The rough knots that disfigure branches are caused by 

 the irritation of these creatures, and some are said to 

 assail the roots. 



The rostrum, or snout, is of the same pattern as in 

 other aphis species, but it is very stout and strong, and 

 at the tip has stiff, rough hair.s, as shown in Fig. 3. 

 Pressure in mounting opened the gap wider than ic is in 

 nature. Some curious structures are fotmd. ou the back 

 of the insects. Near the autennse they make jjvetty 



