20 THE AMERICAN MONTHLY [Jan 



ed with the instrument and its manipulation, and that one 

 learns how to see with it. The fact of having a fine mi- 

 croscope and accessories in one's possession, is not evi- 

 dence of ability to use it and work with it. It is well for 

 the medical microscopist to commence with the primitive 

 forms of life and to observe and study them closely. 



The study of the white blood corpuscles can never 

 mean much to the man who has never studied an ameba ; 

 still, there is no reason why every medical man or student 

 should not frequently see this primitive form of life so 

 nearly representing true active protoplasm. Amebas are 

 easily obtained fro'm the horse trough, ponds, or ditches, 

 and may be observed undergoing their characteristic 

 changes in form, and to the student of phagocytosis, ex- 

 amples can often be offered of amebas devouring bacilli, 

 some thriving on them and others dying from the poison 

 developed by the ingested bacteria. It is not alone the 

 white blood corpuscles whose prototype is found in our 

 ponds and ditches. The action of the cilia of ciliated 

 epithelium is difficult to see and understand, yet the vor- 

 ticella, a comparatively large organism will nicely illus- 

 trate a cell of ciliated epithelium. This one-celled animal, 

 wiien expanded, presents a cup-shaped form whose motion 

 is capable of creating currents to or from this cup. 



The fresh water alga? present a good example of pro- 

 creation in their earliest development. The diatoms offer 

 a fascinating field of study. They are valuable as test 

 objects and teach us to observe fine, delicate outlines and 

 structure and to test the defining and resolving power of 

 our objectives. They are common and may be found in 

 both fresh and salt water, in oyster juice, in polishing 

 powder, earth, sand, and in our drinking water. These 

 are profitable studies to the medical man who desires to 

 master his instrument and will teach him to judge accu- 

 rately the value of what he sees and to gain a clearer in- 

 sight into the life of individual cells than he can ever 



