PROF. STRASBURGEr's OBSERVATIONS ON PROTOPLASM. 125 



plasin. The plasniodia of Myxomycetes, especially such as 

 move but slowly, were found by de Bary i and Hofmeister ^ 

 to show evident differentiation into ecto- and endoplasm. 

 Among the Rhizopoda, the Monothalamia Lobosa have indi- 

 cations of such a differentiation in their pseudopodia, and in 

 the true Amoebse, the whole protoplasmic mass, is distinctly 

 differentiated into the two layers. The ciliated cells of 

 sponges also show a separation into the two, ecto- and endo- 

 plasm, the former of which sends out the cilium and forms 

 a collar round its base, as James Clark, Carter, and especially 

 Haeckel have shown. Max Schultze^ goes so far as to say 

 that a cortical layer appears to be differentiated in every 

 mass of protoplasm which is functionally a cell, but this is 

 not of universal occurrence, although it is very frequently 

 the case. Prof. Strasburger, in opposition to Max Schultze's 

 view, brings forward some of the Rhizopoda, such as the 

 Heliozoa, which consist wholly of granular protoplasm, that 

 is, of protoplasm which corresponds to the endoplasm of those 

 forms in which differentiation has taken place. 



Although these various observers are unanimous in assert- 

 ing the frequent presence of the hyaline ectoplasm, they 

 do not all regard it as indicating a true differentiation. 



Hofmeister,^ who pointed out, in opposition to Pringsheim, 

 &c., that the ectoplasm is firmer than the endoplasm, attempts 

 to account for its greater density by ascribing to the proto- 

 plasm the general property of drops of fluid of being more 

 dense towards their surface than towards their interior. 

 Pfeffer^ regards this dense hyaline layer, to which he some- 

 what loosely applies the term " primordial utricle," as a mem- 

 brane of precipitation. He writes, " Protoplasm brought into 

 contact with pure water, or watery solutions, covers itself, 

 by precipitation, with a delicate membrane, the so-called 

 primordial utricle, and this is the case whether the proto- 

 plasm be living or dead." It is evident, however, that the 

 ectoplasm is not so sharply defined from the endoplasm as 

 to warrant the use of the word " membrane " with regard to 

 it, and as a farther objection to Pfeffer's view it may be urged 

 that the ect023lasm, as will subsequently be shown, often 

 possesses a structure which is entirely different from that of 

 the endoplasm. Prof. Strasburger goes on to give an account 



' ' Mycetozoen,' p. 41. 18G4. 



2 'P&anzelle/ p. S, 1867. 



3 ' Protoplasma,' p. 58. 18G3. 

 ■* ' Pflanzeiizelle,' p. 3. 



'■ ' Silz. der Niederrheinisclien Gesellschaft fiir Naturwiss. zu Bonn,' 

 1S75. 



