34 PRACTICAL HISTOLOGY. 



exterior of the clump (Fig. 8, b) ; and as the filament gets 

 a little longer and projects more the remains of the disk 

 may often be seen forming an enlargement near its middle. 

 Soon some of the projecting filaments begin to oscillate 

 in the liquid, and at length break away altogether from 

 the mass, and continuing their oscillatory movement in 

 the surrounding fluid, become gradually more and more 

 removed from the clump, until they may eventually .even 

 pass altogether out of the field of the microscope. Mean- 

 while other of the disks have grown out into filaments 

 and taken the place of the liberated superficial ones, and 

 soon these in their turn become free and give place to 

 others ; so that in this way the previous solid-looking 

 mass becomes almost entirely broken up into freely-mov- 

 ing filamentous particles (Fig. 8, c). These are not all 

 of the shape above described, but present various forms, 

 as shown in the accompanying figure. 



The above observation shows that the discoid parti- 

 cles which are occasionally found in theblood^and which 

 when the blood is drawn tend to become collected into 

 clumps, are to be regarded as centres of origin from which 

 minute, filamentous, bacterium-like organisms may under 

 some circumstances be developed ; but whether this change 

 ever occurs in the living body, and what further modifi- 

 cation the filaments may, under conditions more favorable 

 for their development, undergo, is at present undeter- 

 mined. 



After the observations recorded in the preceding 

 paragraph are completed, the action of an excess of 

 heat may be observed; but it is better to use for 

 this purpose a larger apparatus, in which the degree 

 of heat can be measured by a thermometer. Such a 

 one is shown in Fig. 9. In this the preparation is 

 placed upon the brass box , which rests on the stage 

 of the microscope, and is pierced in the centre by a 

 tubular aperture, to admit light to the object. The 

 box is connected by India-rubber tubes with a hollow 

 metal jacket, /, and the whole system thus consti- 

 tuted is completely filled with water previously 

 boiled, to the exclusion of air. The water is warmed 

 at q l>v n small gas- flame, and rising through the tube 



t/ / ,~ 



