212 THE MICKOSCOPE. [October, 



along the axis of the microscope, placed in the horizontal position ; 

 the Abbe condenser projects an image of the sun upon the plane 

 of the stage ; the objective and field lens of the eye-piece form a 

 second image in the plane of the diaphragm, and lastly the front 

 lens of the eye-piece produces a third image on the ground-glass 

 of the camera. Between the front lens and camera is interposed 

 a direct-vision spectroscope. The eye-piece employed was a 

 special projection one of Zeiss, which consisted of two lenses giv- 

 ing a system perfectly aplanatic and achromatic. For taking 

 absorption spectra the transparent solid or liquid under examina- 

 tion is placed on the stage of the microscope. 



NCV/S TRO/A 

 THE Vs/ORKEJ^S 



The Protozoa— a Phylum of the Animal Kingdom Considered 



Biologically. 



Prof. Henry L. Osborn, of Hamline, Minn., has described the 

 Protozoa in the Ajnerican Monthly Microscopical yournal 

 for October. Among other things, Mr. Osborn says : 



It woidd seem very remarkable, indeed, if we were not now 

 used to the conception that there are so few different kinds of ele- 

 mentary substances and so few different elementary principles. 

 The early mind' looked on all observed differences as radical and 

 indicative of fundamental and essential unlikeness in things ob- 

 served. This quality of mind persists to-day in rudimentary peo- 

 ples and in the untaught and unobservant of more advanced races. 

 But the person who lives in the light of the present era of scien- 

 tific thought expects that the complex will upon inspection resolve 

 itself into the simpler and finally into the simple. If we examine 

 any single member of the higher groups of animals or plants, we 

 find that, complex though they maybe, their actions are the alge- 

 braic total of the powers of the multitudes of cells which compose 

 them. Cell growth and reproduction, tissue work, division of 

 labor, comprehend activities in plants or animals which in the 

 total we speak of or think of as the creature's life. 



Side by side with this idea of the biology of an animal or plant 

 as the sum of the activities of component similar cells or really 

 prior to it at the outset, though of slower growth, is the comple- 

 mentary conception which sees groups of animals or plants as the 



