METHODS. 3 



disproves the opinion of many histologists that the nucleus is something 

 essential to the so-called " unicellular " organism. Haeckel's view, viz., that 

 there is a marked difference between forms devoid of a nucleus, termed by 

 him "cytodes," and those with nuclei, termed " cells," must be considered 

 to be untenable. 



Moist Chamber. Von Recklinghausen invented the moist 

 chamber for the purpose of preventing microscopic specimens 

 from evaporation, without cutting off the supply of air. Many 

 devices have been invented for this purpose. One of the simplest 

 is L. Ranvier's a slide on which a circular furrow, for holding 

 air, surrounds the central plane surface ; on the latter a droplet 

 of the liquid is placed, and the covering-glass, which must be 

 large enough to cover the whole of the furrow at its edges, is 

 hermetically sealed to the slide by a frame of melted paraffine. 

 S. Strieker uses a slightly elevated frame of glazier's cement, on 

 the top of which he sticks the covering-glass holding the speci- 

 men, while a droplet of water on the bottom of the chamber 

 supplies moisture. The same investigator uses a moist chamber, 

 which, for examinations not exceeding one or two hours 7 dura- 

 tion, proves to be the best and simplest of all. He oils the edge 

 of one side of the covering-glass, and after having transferred a 

 droplet of the fresh liquid to the slide, he covers it so that the 

 oil-frame of the covering-glass adheres to the surface of the slide 

 around the specimen. 



Heatable Stage. Max Schultze introduced the so-called heatable 

 stage with the view of keeping up in a specimen the temperature 

 of the body, or raising it at will. As a matter of course, liquids 

 of cold-blooded animals, especially their blood, need no such 

 apparatus. A droplet of blood of the newt (triton, salamandra), 

 which we obtain by cutting off the end of the tail of the animal 

 with a pair of scissors, may be transferred upon the slide by 

 simply touching the wound. The specimen must immediately 

 be covered with a very thin covering-glass, the edges of which 

 have been oiled beforehand. With a little skill, a specimen is 

 obtained fit for examination even with the highest powers of the 

 microscope. The warmer the temperature of the room the 

 sooner the colorless blood- corpuscles will begin to change their 

 shape and location. They will prove to be identical with the 

 amoebae found in an infusion of grass. The examination of 

 the colorless blood-corpuscles, or other isolated bioplasson bodies 

 of warm-blooded animals, by means of the heatable stage, has 

 proved their identity also with amoebae. Such bodies within the 



