142 PROCEEDINGS OF THE SOCIETY. 



Mr. Forrest's Compressor) um (received 31st October last and 

 accidentally mislaid) was exhibited and described. It is designed 

 with a view to cheapness, and differs from the Wenham com- 

 pressorium in the action of the spring and screw being reversed, so 

 that instead of the spring putting on the pressure and the screw 

 releasing it, the screw puts the pressure on and the spring releases it. 

 It is claimed that this in practice will be found an advantage as it 

 enables the observer to feel what pressure is put on. 



Mr. Crisp referred to the erroneous statements that had been 

 made as to the supposed advantages of Mauler's blue glass slides in 

 " shortening the wave-lengths and so giving increased resolving 

 power." The fact was that they were intended to be used with 

 objectives affected with chromatic aberration, the performance of 

 which was thereby greatly improved. A letter from M. Mauler was 

 read to the meeting, in which he mentioned that the blue mounts 

 would be found useful in the case of delicate histological preparations. 

 They also agreeably modified the ordinary yellow light of gas and oil 

 lamps. 



Mr. Kitton's note on the use of gum-juniper for mounting 

 diatoms was read. It has an index intermediate between water and 

 balsam, and is soluble in methylated spirit. Preparations may be at 

 once transferred from the spirit to the dissolved gum. 



Dr. Anthony's paper " On the Threads of Spiders' Webs " was 

 read by Mr. Stewart, enlarged copies of the illustrations being di-awn 

 upon the black-board. 



The President said that Dr. Anthony had certainly exercised 

 great ingenuity in his methods of procedure. He believed that the 

 nature of the thread depended upon the spinnerets which were 

 used. 



Mr. James Smith said that, in watching the process of an attack 

 by a spider upon a fly, he observed that, at the commencement, only 

 two or three spinnerets were used to spin the web round the fly. The 

 first portion of the web was like a quantity of floss silk, and then, as 

 the web converged towards the fly it became more like a gut-line. 

 After a while the fly began to struggle, and then the spider used some 

 more web, and finally used all five spinnerets. He thought, from 

 what he had seen, that the quantity or quality of the web depended 

 upon what the spider wanted to use it for, and, according to this, he 

 used more or less of the spinnerets. 



The President inquired whether Dr. Anthony should not have 

 used the word " she " in speaking of the spider. Was it not the 

 female spider which spun the webs ? 



Mr. Stewart said he had often seen the male spider in the middle 

 of a web waiting for his prey, and always thought it was his own web, 

 for he certainly would not venture into the web of a female, knowing very 



