ELEMENTS OF STRUCTURE. 



77 



Fig. 68. Living connective tissue from the frog's leg. ale 

 d e, various forms of connective-tissue corpuscles ; (o-c, 

 contractile) ;/, fibres, and g, bundles of the same ; A, elastic 

 network. 



surrounding medium in which" it floats. The mode in which the little 

 animalcule slowly effects a change of position in the field by means of its 

 contractility may also be recognised. It is observed, namely, to put out 

 a process in one direction, into which the rest of the body gradually 

 streams, as it were, until 

 finally this process has be- 

 come the body of the organ- 

 ism. The interesting disco- 

 very also was made a few 

 years ago, that these two pro- 

 perties are not exclusively 

 confined to the elementary 

 organisms just mentioned, 

 but exist in the less inde- 

 pendent amoeboid cells of 

 the bodies of higher animals. 

 Thus we see that tiny mole- 

 cules of pigmentary matters, 

 such as cinnabar, carmine, 

 indigo, and aniline, or the 

 oil-globules of milk, are taken 

 up into the bodies of the 

 amoeboid cells of blood, of 

 lymph, and of pus, some 

 of them while lying at rest 

 being reached and embraced, 

 as it were, by processes of the protoplasm, and so received into the body 

 of the cell (fig. 69, a). But what is thus brought about artificially with 

 comparative difficulty, takes place readily 

 and extensively in the living body. 

 Closely-packed in the narrow interstices 

 of organs, amoeboid cells receive into 

 their substance even larger formed masses ; 

 these may, however, be forced into the 

 soft protoplasm from without. In the 

 interior of such cells we find at times 

 conglomerations of animal colouring mat- 

 ters, fragments, or even perfect examples 

 of blood-corpuscles, which have left the general circulation (b), objects 

 which were regarded as enigmatical in former times, when the cell was 

 supposed to possess an imperforate membrane. 



With the power of receiving matters into its body there coexists in the 

 cell another of expelling the same. After a certain time the contractile 

 protoplasm works the granules, or fatty molecules as the case may be, 

 towards its surface, and finally discharges them from the body of the cell 

 completely. 



This wandering of amoeboid cells through the interstices of living parts 

 was discovered years ago by ReeklingTiausen. The readiest mode of 

 studying the phenomenon for ourselves is by taking a drop of some fluid 

 containing cells from the body. In the tissues of the system the cells 

 wander on with a continual change of shape through fine narrow inter- 

 stices (usually compressed somewhat into elongated figures), and traverse 

 thus in a short space of time comparatively large distances. 



Fig. 69. a. 



