:3fi 



KNO\VLi:nGE. 



Jim.. 1912. 



but those of the I'hasniid.'io as figured by Kaiip are so extra- 

 ordinary as to t;ive the iiiiprossinn that whoever oriKiiiatcd the 

 drawings must have drawn largely from his imagination, as 

 surely no insect could lay an egg. the flat lop of which is not 

 only baltlenieiited round the margin, but has a veritable cross 

 more than one-fourth the height of the egg itself, standing erect 

 and isolated in the middle of it. 



Having recently received a number of the eggs ol a species 

 said to be Uixippiis iiiorosiis. a microscopical examination of 

 these m.iy be of some interest. In colour they are a dark 

 purple brown, the outer shell having a finely-granulated surface 

 and being very hard and brittle ; cich egg also has upon one 

 side only a. curious cuneiform m.nking bordered with a dark 

 chrome yellow baud, this probably representing the point at 

 which it was originally attached to the ovary. In shape they 

 are somewhat elliptical measuring •lOinch by -oy-inch, the 

 upper end of each being slightly flattened and fitted with an 

 oval cover -OS-inch by ■04-inch, on the top of which is a 

 bright yellow knob, circular in shape with a diameter of 



'.IHI 



A. Large coloured hair with small medullary cells. 



IS. A flat, coloured hair, strongly fibrous, with no medullary 



cells, 

 c. Coloured hair with large medullary cells. 

 IJ. Colourless hair with large medullary cells and sheathing 



cortical cells. 



■02-iuch and -Ol-inch high, looking under the microscrope not 

 unlike the lid of a brown earthenware teapot. The upper 

 surface of the cover is formed of hard material uniform with 

 the shell of the egg, but below this is a thicker layer of rather 

 softer substance, darker in colour and finely toothed round the 

 edge, the teeth fitting accurately into corresponding corruga- 

 tions round the thickened edge of the opening, whilst below 

 this again is a layer of stout white membrane similar to that 

 with which the egg itself is lined. The knob has a deep 

 depression in the centre, a section through which seems to 

 show that at one time there was a perforation through this lead- 

 ing to the interior of the egg. prob.ably in the nature of a 

 micropyle. The use of the knob is not very obvious, as the 

 larva when mature pushes off the cover from the inside, 

 causing it to fall intact, but in escaping from the egg it fre- 

 quently happens that the claws of one or both of the third 

 pair of feet become so entangled in the lining membrane as 

 to oblige the young insect to drag the empty egg shell about 

 with it until artificially relieved. The larva when first hatched 

 is so much larger than it seems possible for the egg to have 

 contained that it is very probable the segments of which the 

 body is composed may overlap each other before emergence, 

 and the great increase in size after changing the skin is per- 

 -haps due to a similar cause. The eggs arc laid separately, 

 and are not attached in any way either to each other or to the 

 place where they are deposited ; the period at which they 

 hatch out seems quite uncertain, as it takes place at all times 

 of the year and is, apparently, not nuich aflccted by the tempera- 

 ture of the air : the young larva resembles the parent except 

 as to size and the absence of wings. It has been said that these 

 insects will occasionally devour those of their own species, 

 but although this has not been conclusively proved against 

 them, it may possibly account for the otherwise mysterious 

 disappearance of sundry small specimens from a box in which 

 others of various ages have been kept together. ij x T 



WHAT IS WtJOL ? — To many of your readers, no doubt, 

 the (|uery which I h;ive used as the title of this note will cause 

 some mild surprise. Textile fibres in immense v.ariety, both of 

 vegetable and animal origin, have been in use from time 

 immemorial, and have been so thoroughly studied in every 

 aspect, optical, chemical, physical and histological, that the mere 

 suggestionas to there beingany doubt asto the definition oiwool 

 will be to many unthinkable. There can be no doubt that wool, 

 besides being one of the best known and most widely used 

 fibres, was also one of the very first to be used by man to 

 protect himself from the inclemency of the weather, following, 

 indeed, very closely upon his first tentative, but unsatisfactory, 

 essay in this direction. One's first thought is, very naturally, 

 that wool is the hair of the sheep, as we are constantly reading 

 of vast quantities of this commodity being imported from 

 Australia, where sheep farming for the sake of the wool is the 

 chief industry. This is, however, far from being the last word 

 on the subject ; for if we make the necessary enquiries we 

 shall discover that commercially, at all events, the term wool 

 is not solely confined to the product of the sheep. Hairs from 

 several animals are described as being wool, no doubt from 

 their having characteristics similar to those from the sheep. 

 I need here only mention that the hairs of several species of 

 goat, such as the Alpaca, Angora and Cashmere, are invariably 

 designated wool ; as are also the hairs of the llama and 

 camel. Indeed, there can be little doubt but that many 

 .animals would furnish hairs which most microscopists would 

 characterise as wool. Failing some authoritative decision on 

 the point, it would appear that we can only fall back on the 

 physical and microscopical characteristics of the fibre. In 

 ihis connection it must not be forgotten that even the hairs of 

 the sheep difler within fairly wide limits according to climatic 

 and other conditions, the principal of which, no doubt, would 

 be the breed of the sheep. Some of the laiger and stouter 

 show strongly marked medullary cells, with the overlapping 

 cortical scales but weakly developed, while in the finer fibres 

 there is an entire absence of the central, but the cortical cells 

 arc strongly developed. In what is recognised as the best 

 wool from the sheep, a careful examination will show that the 

 hairs have a soft, slender, \va\y appearance, and microscopically 

 the medullary, or central cells, are either absent or at least 

 not strongly marked, w^hile the cortical cells are well- 





Figure 263. 



i;. Colourless hair with smaller medullary cells and well- 

 marked cortical cells. 



I'. Large colourless hair with no central cells, but with fine 

 and close cortical cells. 



G. Fine hair with well-marked sheathing cortical cells. 



H. Fine hair, similar to the last, but with finer cortical cells. 



developed as sheathing scales, overlapping each other so as 

 to give a finely-serrated appearance to the margin of the 

 filament, and an appearance of fine, sinuous lines crossing 

 the fibre. .Any hairs having these characteristics would 

 unhesitatingly be pronounced wool by most microscopists. 

 and from a histological standpoint, they would bo fully 

 justified. There can, however, be little doubt that whenever 

 the term wool is used in a commercial sense, without any 

 qualification, the hair of the sheep is invariably meant. In an 

 earlier part of this note, it was suggested that many animals 

 on some parts of their bodies would furnish hairs with a very 

 decided wool-like structure, which, if submitted toa microscopist. 



