The Microscope. 247 



his experiment, and that he will find the objects so often men- 

 tioned, rendered easy of examination. Petals and other parts 

 of the flower need no previous preparation. It is well however 

 to cut the leaves so that there shall be two or more open surfaces 

 for the penetrating of the glycerine. In some very delicate 

 specimens this will not be necessary ; it is so when the leaf is 

 thick or very opaque. 



Acknowledgment. — To Mr Fr. Dienelt, of Loda, 111., for 

 several insect preparations. Mr Dienelt is doing excellent work 

 in insect anatomy, especially in connection with tracheae that 

 are internally hairy. The list of insects in which these inex- 

 plicable appendages are found is a long and lengthening one. 

 The subject seems to have attracted absolutely no attention till 

 brought to light some time ago in The Microscope. — To Prof 

 John H. Miller, Ph. D., of Buffalo, N. Y-, for a slide of tube 

 casts, stained and mounted in balsam. 



NEV/S • FRP/A- 

 THEVVbRKCI^S 



The ventricles of the frog's brain and the central canal of the 

 spinal cord are lined by a ciliated epithelium which has recently 

 been studied by A. C. Wightman^ who states that it forms a 

 continuous lining to the central nervous system, being a single 

 layer of ciliated cells in thickness ; those of the ventricals form 

 a central zone, about which the brain cells are concentrically 

 arranged ; the cells of the epithelium and of the brain are con- 

 nected by often branching processes extending from the tips of 

 the former ; the epithelial cells being columnar, spindle-shaped, 

 and of intermediate forms. The cilia of the living cells beat at 

 the rate of from one hundred to two hundred strokes per minute. 

 No wave of ciliary movement is visible, each cilium acting inde- 

 pendently of every other, and often at a different rate. Each 

 beat consists of a quick stroke and a somewhat slow recovery, 

 the vigorous strokes being always directed posteriorly. 



1 studies Biol, Lab. Johns Hopkins Unir. 



