512 



SUMIIARY OF CURRENT RESEARCHES RELATING TO 



definite plane is projected upon the corresponding diameter of the described 



circlG, 



The employment of definition surfaces renders possible not only accu- 

 rate reconstruction but also determines the change of form of the whole 



Fig. 152, 



Fig. 153. 



object, the position of its various parts in the successive sections, and even 

 allows the size of the angle about which the object has turned to be 

 calculated. 



Reeves, J. E. — How to work with the Bausch and Lomb Optical Co.'s Microtome, and 

 a method of demonstrating the Tuhercle Bacillus. 



27 pp., 8vo, Rochester, N.Y., 1886. 



(4) Staininir and Injecting*. 



Ahsorption of Anilin Pigments by living Vegetable Cells.* — Dr. W. 

 Pfeffer continues his researches on this subject, using for his experiments 

 solutions of one part in a million of the pigment, and in the case of methyl- 

 violet, one part in ten millions. If the pigment which enters the cell remains 

 unchanged, the concentration must remain the same inside and outside the 

 cell, and no staining could be detected under the Microscope. Any tinging 

 of any part of the cell must be due to a chemical change in the pigment ; 



* Unters. Bot. Inst. Tubingen, ii. (1886) pp. 179-331. Cf. this Jourual, ante, p. 172. 



