270 



HAEDWICKE'S SCIENCE -GOSSIP. 



getlier. When they are few iu number, and of 

 various sizes in the animal, they form a novel and 

 pleasing sight as they are carried up and down by 

 the current before mentioned in the perigastric 

 space ; at times revolving with great rapidity on 

 their own axis, and at the same time round one 

 another. Frequently a group of five or sis may be 

 seen revolving together. Some of them are per- 

 fectly clear, others are partially covered with small 

 globular forms of a brighter appearance than the 

 globe itself. The largest of them are sometimes 

 marked with irregular patches of various shapes, 

 and as they revolve on their axes, it gives them the 

 appearance of a miniature world. A few show an 

 opening (p), by which they are seen to be empty 

 hollow globes, but what they really are is not 

 known. 



On being alarmed, the Lopkopus quickly retracts 

 within the transparent cell (s), and again protrudes 

 when all is quiet, unfolding its beautiful crown of 

 tentacles, in the course of which movement the 

 action of the muscles is plainly seen (e). The 

 expanding of the tentacles immediately on the 

 protrusion of the polypide from its cell is one of 

 the most pleasing sights that can be presented to 

 the observer, as the cilia with which they are 

 studded are instantly in full play, passing up on one 

 side of the tentacle from the base to the tip, and 

 down the opposite side, like an endless chain, 

 thereby forming the vortices in the water by which 

 the particles of food are brought to the mouth. 

 Sometimes the colony consists of from six to twelve 

 polypides, and will divide into two colonies, com- 

 mencing the division at p, and slowly separating 

 down to the point where it is fixed to the plant, 

 &c., each part moving in opposite directions. They 

 then propagate by gemmation or budding. This 

 process is very interesting to watch, from the first 

 appearance in the parent to the issuing of the young 

 from the newly-formed cell. When the minute 

 tentacles of the young are exserted, they form a 

 beautiful contrast to the fully developed of their 

 parents. Though small, yet the same functions are 

 visible in relation to digestion, &c., as in the older 

 ones. 



I would advise those lovers of natural history 

 who possess a microscope and live iu a neighbour- 

 hood where there are shady dykes or a millpool, 

 &c., to search for them ; when found they will am- 

 ply repay the trouble iu the pleasure they afford 

 in observing and investigating their wondei'ful 

 mechanism and marvellous beauty. No pencil can 

 portray nor pen describe them. I have had them 

 under observation for over three months, have seen 

 some of the colonies die out, and have their stato- 

 blasts iu glass cells, from which I anticipate the 

 pleasure of seeing the young Polyzoa emerge iu 

 due time. 



Tu endeavouring to show the position of the 



mouth in the sketch (k) I have left out the continu- 

 ous line of tentacles at n, where, to complete the 

 crown, they should be continued quite round ; bu t 

 then the mouth could not be seen, only the region 

 of the mouth, as shown at a. Transparent as those 

 creatures are, they are covered by a still more 

 transparent envelope (k), which escaped my obser- 

 vation until my attention was called to some 

 Forticella and Rotifer vulgaris that were attached 

 to something near the LopJiopus, which on closer 

 examination proved to be the outer envelope which 

 entirely covers them, with the exception of the 

 orifice of the cell. The Rotifers, being attached to 

 an almost invisible substance, become very interest- 

 ing objects. The muscles of LopJiopus, when the 

 polypide is fully exserted, are seen drawn tight, and 

 have the appearance of fine glass threads ; when 

 retracted within the cell (/), the muscles are relaxed 

 and bent {e). 



Canterbury. James Eullagae. 



THE DIADEM SPIDER. 



{Epeira diadema.) 



y EUWENHOEK, about the beginning of the 

 -" last century, jrecognized only five species of 

 spiders. More than two thousand years before this, 

 Aristotle had, in the ninth book of his zoological 

 work, described eight kinds — spiders, doubtless, 

 found in Greece, and with which the philosopher 

 was practically acquainted. Eighty years of the 

 eighteenth century had scarcely elapsed before Dr. 

 Berkenhout described twelve species as indigenous 

 to this country, first and foremost among which he 

 placed the Diadem Spider. Although these two or 

 three native spiders have now increased to several 

 hundreds, yet JEpeira diadema, considered histori- 

 cally, and economically too, perhaps is the jnost 

 interesting of them all. 



The ancient naturalists had often watched a 

 spider that was wont to spread its snare from tree 

 to tree, to wait, motionless, for many an hour in 

 the centre of its web, and, when an insect was un- 

 fortunate enough to become entangled, to rush up 

 and envelop it in threads. This, one of the largest, 

 brightest, and commonest of the geometers, could 

 not have failed to attract their attention. The 

 Diadem Spider adorns our gardens in the autumn 

 with a web intricately woven, yet wonderfully simple 

 as a whole. It is suspended perpendicularly, or 

 somewhat obliquely, from plant to plant, from wall 

 to wall; the denizen, head downwards, occupies 

 the centre, or is concealed by the duplicature of a 

 leaf. 



The question may be asked, why does the spider 

 invariably watch in an inverted position ? The Abbe 

 La Pluche has attempted to explain this ; he says, 

 the abdomen in any other attitude would fatigue her 



