The Microscope. 89 



microscopical imps would be excusable after the microscopist 

 had tried for three hours to follow them up to get some notion 

 of their shape and structure. When killed by the acetic acid 

 they are seen to consist of two parts, a body which is very 

 similar to that of the common Spirillum , although at times and 

 when the animalcule is dying, it shows that it is flexible and 

 capable of assuming new coils or of imperfectly staightening 

 itself When dead it lies in a long loose incomplete coil, or in 

 an undulating line. It has no mouth, no nucleus, no contractile 

 vesicle, no internal organs, and onl}^ a single external append- 

 age, that which produces its lightning-like movements. This 

 appendage is a narrow membrane attached in an undulating 

 course to one side of the Spirillum-like body, but not, as some 

 investigators have said, encircling the body spirally. It is 

 attached to one side only. Its edge is thickened and the whole 

 membrane, as the reader will soon learn if he attempts to see it 

 during its life, is exceedingly flexible and movable. After 

 death by acetic acid the creature, as well as its vibratile append- 

 age is plainl}' visible with a good 1-5 objective, especially when 

 the microscopist has, with a higher power, learned what to look 

 for. 



The parasites are worth the slight amount of labor needed to 

 see them, not only because they are so lively and so exasperat- 

 ing, but chiefly because they are parasitic within the oyster that 

 everyone is fond of, although the little creatures will not add a 

 single titillation to your gustatory nerves as their host slips 

 down your throat ; the^' are inside the victim and only 1-200 

 inch in length at the longest, while some are not more than 

 one-third that length. Yet the thought that you are swallow- 

 ing them when you swallow it may add interest to the act, 

 especially after you have seen them. 



Acknowledgment. — To Messrs. James Stratton & Son, 

 Brooklyn, N. Y., for an additional reservoir for their beautiful 

 and convenient microscope lamp recently noticed in The Micro- 

 scope— To Mr. E. H. Griffith, of Rochester, N. Y., for his focus 

 indicator. This is a simple little instrument, but one that 

 should excite admiration by that simplicity and by the ease 

 with which it accomplishes its purpose. It consists of a flat ring 



