Vitality and Organization of Protoplasm. 45 



which give rise to the essential vital properties of the living substance, 

 of which all organisms are admittedly composed. These properties, 

 which constitute protoj)Iasni tl.e on e living_ suii^iiLce in nature, and 

 which are, in fact, tlic essential vital properties of all organism?, reveal 

 themselves intelligibly in the morphologically uncomplicated and trans- 

 parent forms of amoeboid beings. Here the sundry vital functions are 

 not morphologically specialized in intricately organized structures, and 

 to all appearance separately confined in definitely formed organs, but 

 are still interdependently fluent to our view. And this allows their 

 mutual relations and activities in the service of the organic whole to be 

 satisfactorily ascertained and scientifically explained. 



DEPUEATIOX. 



To complete our understanding of the cycle of chemical activities that 

 constitutes vitality, we have to gi\e a moment's attention to depuration, 

 the other indispensable adjunct to vital activity besides nutrition, and 

 well nigh its opposite, though interdependently connected with it. Dur- 

 ing functional activity, during its functional interaction with the me- 

 dium, the living substance becomes to some extent deteriorated. The 

 effete products of this functional deterioration have to be eliminated, in 

 order to keep the living substance undefiled and unimpeded in its activ- 

 ity. This is one of the occasions for depuration. Moreover, the process 

 of nutrition, during its elaboration of assimilable material, gives like- 

 wise rise to the formation of effete products, which have also to be elim- 

 inated. This is the second occasion for depuration. The functionally 

 severed particles of organic substance are seized upon by oxygen and 

 reduced to eliminable elements. 



There are, therefore, two different regions, and two different occa- 

 sions, where and when depuration takes place ; the first, where what may 

 be called the dynamical play with the medium occurs; and the second, 

 where the nutritive processes are at work. The former we may designate 

 "dynamical," the latter- "nutritive" depuration. In Protozoa these 

 functions are in most cases visibly performed by depurative vesicles, 

 which gather and eliminate the oxydized and fluidized waste products. 

 In amoeboid beings the depurative vesicles, or so-called vacuoles, indis- 

 criminately arise more or less numerously where and whenever needed. 

 In ciliated Infusoria, however, they become definitely localized, and con- 

 stitute then regularly functioning organs. In some, as in the Vorticelli- 

 dae, one single pulsating vacuole ministers normally both to dynamical 

 and to nutritive depuration. In others, as in Paramsecidse, a vacuole in 

 the oral region ministers to dynamic depuration, and another in the 

 aboral region to nutritive dejxiration. 



In Actinophrys sol, when the animalcule has first been made to shrink, 

 the formation and eventually the definite localization of the depurative 

 vacuole can be observed. This interesting localization of an organ in 

 the making, I have described in the St. Thomas Hospital Eeports, 1879. 



Besides the two modes of fluid depuration occurring in Sarcodina, 



