524 SUMMARY OF CURRENT RESEARCHES RELATING TO 



direct-acting screw fine adjustment, and a substage focusing by means 

 of a sliding tube. 



The Austrian is more expensive than the Berlin maker, but, on the 

 other hand, he gives you more for your money. A lever is interposed 

 in the fine adjustment, the substage has screw focusing as well us 

 centring adjustments, and the main stage has a sliding bar. 



In the English group, Baker, Swift and Watson all have a more 

 complex fine adjustment than that of the ordinary Continental type ; 

 but they have only sliding-tube focusing arrangement to their substages. 

 Beck's, on the other hand, retains the Continental form of fine adjust- 

 ment, but adds the screw focusing adjustment to the substage, and that 

 at a price lower than any similar class of Microscope of either British or 

 foreign manufacture. 



*&' 



C z a p s k i, S. — Grundziige der Theorie der Optischen Instrumente nach Abbe. 



Leipzig : Job.. Ambros. Barth, 2nd edition, xvi. and 490 pp. 



Die prazisionsmechanik und optik auf der Weltausstellung im St. Louis. 



Deutsche Mechan.-Zeit, 1904, p. 181. 



Hageb, H. — Das Mikroskop und seine Anwendung. 



Berlin: J. Springer, 1904, 9tb edition, 392 pp. (401 figs.). 



Niemann, G. — Das Mikroskop und seine Benutzung in pflanzenanatomiscben 

 Unterricbte. Magdeburg (Creutzsche Verlagsbuchhandhing) 1904. 



Reinisch, R. — Petrograpbisches Praktikum. ZweiterTeil: Gesteine. 



Berlin, Gebru. Borntr'ager, 1904, vii. and 180 pp. (22 figs.). 



RHEiifBERG, J. — The Collected Papers of Abbe and Microscope Theory in Germany. 



[The author has translated into English Dr. Ambronn's review (Zeit. f. wis. 



Mikr., January 1905) of the collected papers of Professor Abbe, published 



last year.] Journ. Quekett Micr. Club (March 1905) pp. 153-66. 



Treadle — British versus Foreign Microscopes. 



[Adversely criticises the heavy horseshoe foot and spring clips to stages. He 

 advocates a sliding bar, and with regard to a tube fitting substage he says 

 that " it is a great advantage if it screws, not into the stage itself, but into 

 a fiat ring screwed to the stage, the holes in the ring, through which the 

 attaching screws pass, being quite loose to the screw shanks. Then the 

 tube, with the condenser in place and focused, can be made to centre 

 exactly, once for all, to, say, the i objective, and. made fast." He is of 

 the opinion that a lever fine adjustment is very much superior to any 

 direct-acting screw.] English Mechanic, lxxxi. (1905) pp. 312-13. 



B. Technique.* 

 (1) Collecting: Objects, including - Culture Processes. 



Spontaneous Action of Radio-active Bodies on Gelatin Media. f 

 J. B. Burke calls attention to his interesting experiments on the action 

 of radium salts on nutrient gelatin. In from 1-4 days there appears a 

 culture-like growth, the nature of which is obscure. The bodies, as seen 

 in the illustration, are round and possess a nucleus. They are soluble in 

 water, and when they attain a certain size, subdivide. They disappear 

 on heating and on exposure to sunlight, but reappear after a few 



* This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses; (2) Preparing Objects; (3) Cutting, including Imbedding and Microtomes ; 

 (4) Staining and Injecting; (5) Mounting, including slides, preservative fluids, &c. ; 

 (6) Miscellaneous. 



t Nature, lxxii. (1905) pp. 78-9 (3 figs.). 



