452 



see Mann's device for adapting Adams's idea of portability to 

 Cuff's microscope. The name S, Johnson is engraved on the 

 stage -plate, and it is almost certain that this microscope was 

 the property of the celebrated Dr. Johnson. 



Mr. C. F. Rousselet said the instrument described was not so 

 substantially built as Cuff's. It was probably designed to be as 

 portable as possible. In this case the stage is movable and not 

 the body, as in Cuff's. It was a very interesting model. 



Mr. C. D. Soar said that focusing by moving the stage is quite 

 common in instruments of this date. Mr. Earland having sug- 

 gested that Johnson was not a particularly uncommon name, and 

 questioned the possible identity of S. Johnson with the Dr. John- 

 son, Mr. T. Court, the owner of the instrument, said that he 

 bought it at Lichfield from a family who had had it for over one 

 hundred years, and who bought it at a local sale of the effects of 

 a friend of Dr. Johnson. All the accessory apparatus is complete 

 and in good condition. 



Mr. J. W. Shoebotham, N.D.A., gave "A General Account of 

 the Spring-tails (Collembola)." He explained the position of the 

 Collembola in the animal kingdom, describing them as belonging, 

 with the orders Protura and Thysanura, to the sub-class Aptery- 

 gota, of the class Insecta. After pointing out the main characters 

 of these orders, the various parts of the Collembola were described 

 more fully. Accounts were given of the eyes, post-antennal organ, 

 pseudocelli, antennal organs, body, legs and those very typical 

 collembolan organs the ventral tube and the spring. Mention 

 was made of the tracheal system, which is present but very 

 poorly developed in a few species, but is absent in the greater 

 number. In those species which have it in more or less rudi- 

 mentary condition, the spiracles are to be found on the under side 

 of the head. 



A great variety of colour is exhibited by these insects, all 

 colours from black to white being found. The order is interesting 

 as containing one of the smallest known insects, namely, Meyalo- 

 thorax Tninimus, a species recently added to the British fauna, 

 and which measures only 0*25 mm. (yjjj in.) The Collembolg, 

 have generally been regarded as scavengers only ; but recently 

 considerable evidence has been brought forward to show that 

 they may do considerable damage to growing crops. In Ireland 

 they have been found feeding on the leaves of tobacco plants. 



