SCIENCE- GOSSIP. 



2 59 



soon be found that a bright green patch is left just 

 at the tail end of the receding fluid. This patch 

 must be immediately sucked up with the pen-filler 

 and transferred to a test tube of clean water. The 

 process may be repeated over and over again as long 

 as the green patch forms, and it will soon be found 

 easy to collect the patch in any part of the saucer. 

 It may be useful to thoroughly shake the liquid 

 between the operations, to release any desmids that 

 may have got entangled in the flocculent matter. 

 After a little while the patch will cease to form, 

 showing that most of the desmids have been re- 

 moved. On examining the small quantity of 

 material drawn off with the pen-filler it will be found 

 generally to consist of desmids in a remarkable state 

 of purity. All the flocculent matter will be left 

 behind, unless a little may have accidentally got 

 drawn up with the desmids, and this can generally be 

 avoided with care. 



The only objects still mixed with the desmids will 

 consist of (a) Sand grains, which, fortunately, have 

 not been very abundant in the material I have 

 worked on. It is advisable to avoid introducing them 

 when out collecting. This is attained by not gather- 

 ing from the mud at the bottom of the pools. If any 

 sand is present, the best way of separating it is to 

 stir the desmids up in a small quantity of water and 

 to pour this off after the sand has settled, but before 

 the desmids have had time to do so. (i) Diaio- 

 maceae. — It cannot be reasonably expected to sepa- 

 rate desmids entirely from these, nor can their presence 

 be said to mar the beauty of the slides, (c) Loricae 

 of rhizopods, &c. — The pretty pear-shaped Difflugia 

 and other rhizopods often occur mixed with the 

 desmids, and to my mind rather add to the interest 

 of the slides. 



(To be continued. ) 



PALPI OF MALE SPIDERS. 



By Edward H. Robertson. 



A MONGST other interesting objects in my micro- 

 -'■*- cabinet are sundry male spiders. I must 

 frankly admit that I am no arachnologist, that is to 

 say, so far as classification is concerned ; my studies 

 of these creatures having been confined to observa- 

 tions on their habits and instincts. I am tolerably 

 familiar with their structure, having devoted special 

 attention to those curious organs, the palpi of the 

 male, most of which are exceedingly complicated in 

 their forms, apparently aimlessly. Yet the most 

 complex can almost invariably be resolved into four 

 or five separate parts. Popularly they may be said 

 to consist of an upper cup-shaped joint, a second 

 joint into which the first shuts up, like the inner case 

 of a watch, and a third or fourth portion correspond- 

 ing to its outermost case. There are few observant 

 naturalists who have not watched in the gardens and 

 fields with interest during the hot summer months 

 the curious antics and acrobatic performances of 

 certain vagrant spiders that appear to be trespassing 

 on their neighbours' preserves. No errant wanderers 

 are these ; but the males in search of their mates, 

 which by some mysterious instinct they discover 

 from long distances. To give a single instance of 

 their courtship, let me describe what I have myself 

 observed. In a quiet nook in my garden in Oxford- 

 shire was the turned-up root of an enormous tree 

 that formed a comfortable armchair. Before me was 

 the brickwork of a pit, from which the wooden frame- 

 work had been removed, and upon the walls was 

 placed a layer of slates to protect the masonry from 

 the weather. Here the female spiders of certain 

 Lycosae congregated. For hours they would bask 

 in the scorching sun rays without moving. I saw 

 suddenly appearing above the edge of a slate, at 



some four inches from where a female was enjoying 

 the heat, four hairy black legs, quickly followed by 

 the black cephalo-thorax of a male Lycosa. In an 

 instant its whole body followed. The creature now 

 halted, as if to reconnoitre ; then, very cautiously as it 

 seemed, approached the female, who appeared to be 

 quite oblivious of her suitor's presence. It was not 

 so, however, for presently, with a velocity so great 

 that the eye could not follow the movement, she 

 dashed at him, and he, with like celerity, disappeared. 

 The female Lycosa returned to her post, but the 

 other spider was not to be discouraged or baulked, 

 for an instant or two later the black legs and head 

 reappeared over the edge of the slate, only this time 

 much nearer to his future spouse. The same tactics 

 were again and again repeated until, wearied of 

 watching this seemingly endless courtship, I arose, 

 and prepared to move away. At that moment the 

 male Lycosa had approached so near the female that 

 with a dash he captured her. 



In some species of spiders the palpi of the males 

 externally in no wise differ from those of the females, 

 except in the possession, on the inner side of the termi- 

 nal point of each palpus, of a tubercle, closely resem- 

 bling in shape the nozzle of a glass syringe. From 

 this simple form we may trace a long series more 

 complex, until we at length arrive at those so com- 

 plicated in appearance, that it would seem as though 

 nature had cast together pell-mell a number of 

 shapeless lumps, knobs, and excrescences, had 

 indeed exhausted her resources in producing some- 

 thing grotesque, and destitute of either utility or 

 beauty. Yet beneath this seemingly purposeless 

 waste of material there underlies a purpose which 

 subserves some definite end. The functions of these 



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