•236 The Microscope. 



agrees with my own views and observations. I may therefore be 

 permitted to state that I accept the opinion of von Mohl con- 

 cerning the general structure of the cell. If some day a cell is 

 found which has no membrane and nucleus, I will say with von 

 Mohl that such a cell possesses only one element, the protoplasm, 

 but if this protoplastic mass shall have organized the two other 

 elements, the membrane and the nucleus, then again I say with 

 von Mohl, that these two must be regarded as distinct structures 

 in the cell. A typical and comjDletely developed cell, therefore, 

 contains these three elements : a membrane, protoplasm and a 

 nucleus. 



There should be no great difficulty in pointing out, at least 

 anatomically, that portion of a cell called the protoplasm ; in fact, 

 I imagine the reader has not even waited for me to state that 

 the protoplasm in a cell is that portion which is found between 

 the membrane and the nucleus ; and this is correct if we have 

 t>efore us a cell in which there is no intrusion of foreign sub- 

 stances, and no elaboration of other substances in the protoplasm, 

 such as aleurone, starch, chlorophyll bodies, etc. 



Protoplasm is organized. We have already seen that proto- 

 plasm has a structure, i. e.. it is organized. In fact, we may dis- 

 tinguish in protoplasm a fibrous network, which for want of a 

 better term may be very appropriately called reticulum. The 

 meshes of this reticulum are filled with a plastic fluid, which is 

 granular, and to which Carnoy has given the name enchylema. 

 A rough but sufficiently exact idea of the structure of proto- 

 plasm may be obtained by imagining a most delicate sponge in 

 which the spongy framework is replaced by a simple and very 

 •delicate network of fibres, and the rneshes filled with a hyaline, 

 viscous and granular substance. There is no difficulty in ob- 

 serving this structure ; the class of animals presenting it most 

 strikingly are the Arthropods. This fibrous structure of proto- 

 toplasm has formed the subject of discussion ever since it was 

 iirst observed by Remack. 



The question has been raised as to whether these fibres are 

 separate, and only irregularly distributed in the protoplasm, or 

 whether they constitute a true network. Flemming leaves the 

 question undecided. He declares that after having studied the 

 Cytology of Arthropoda, there remains no doubt in his mind 

 concerning the true reticulate nature of the protoplasmic fibres. 



