288 M. E. Claparede on Actinophrj^s Sol. 



Actinophrys Sol and Amoeba diffluens), and the shell-bearing 

 forms (at least Arcella) are also probably destitute of this struc- 

 ture, but the opacity of the shell in most of these prevents us from 

 arriving at any certainty. Kolliker himself was aware of these 

 facts, nevertheless he regards the Rhizopoda, like all the other 

 Infusoria, as cells. But then, I would ask, what remains as the 

 characteristic of a cell, if both nucleus and membrane may be 

 wanting at the same time ? Kolliker indeed raises the question, 

 whether it be not possible that the young Rhizopoda are true 

 cells, and that the nucleus and membrane afterwards disappear, 

 as is the case, for instance, with the nucleus in the blood- 

 corpuscles of man. We may conceive the possibility of this, 

 but where do we find any proof it ? Has any observation sup- 

 porting it ever been made ? Ehrenberg himself, to whom it was 

 of such importance to find sexual organs in his Polygastiica, 

 admits that he could never clearly make out the seminal glands 

 (nucleus) of Actinophrijs. Very small individuals (and I have 

 had them much smaller than those observed by Kolliker) treated 

 with dilute acetic acid exhibited no trace of a nucleus. This 

 supposition, that Actinophrys and other Rhizopoda pass through 

 a previous cellular condition, has consequently no foundation in 

 fact. 



A cell consists of three parts, — nucleus, membrane, and con- 

 tents. If Kolliker asserts that the coexistence of these three 

 parts is not indispensably necessaiy, and that even two of them 

 may be deficient, — that, for example, we may attribute the sig- 

 nification of a cell, to the contents remaining alone, and con- 

 tained in nothing, — I must confess that such an idea is beyond 

 my power of conception. A cell without nucleus and membrane 

 appears to me to be much the same as a man without body and 

 soul, a thing which perhaps may be, but will certainly be no 

 man. If, therefore, with Kolliker, we regard the Rhizopoda as 

 a class of unicellular animals, the organisms which it includes 

 will be principally distinguished by their having nothing to do 

 with cells, as they consist of a shapeless mass of a structureless 

 homogeneous substance. 



Kolliker, however, refers all Infusoria to his class of uni- 

 cellular animals. He does not even support his view by ar- 

 guments; for he assumes that the fact "cannot be subject to 

 the slightest doubt, with any one who will only examine an 

 Opalina, a Bursaria, a Nassula, &c., pretty closely." Never- 

 theless, we shall ventiu-e to put forward some opinions upon 

 this subject. We are not yet convinced that in Loxodes bur- 

 saria, the so-called chlorophylle grains are not chlorophylle 

 vesicles (they often occur perfectly colourless), with which the 

 wall of the body is covered. They are closely attached to this 



