PLASMODIA OF ^THALIUM 113 



nodal points of the framework stand out very prominently in 

 many places. Towards the edge the framework becomes paler 

 and more finely meshed. Finally, a broad, apparently quite 

 homogeneous border forms the exceedingly attenuated edge 

 of the lobe, of which the outer, very delicate limiting contour 

 is only just visible. But by careful examination distinct traces 

 of foam-like structure can still be made out in the photograph in 

 this apparently hyaline margin. In many cases, however, I saw 

 this structure still better than in the present photograph, for 

 which reason I do not doubt that an apparent absence of 

 structure in the margin only depends on the faintness and fineness 

 of the framework, which is caused by the excessive thinness of 

 the margin. We shall soon see that a further fact of importance 

 is in favour of this assumption. 



Photograph XV. should now be compared with Photograph 

 I., in order to convince oneself of the striking resemblance of 

 the two in all the points mentioned. 



We may now consider Photograph XVI., which represents 

 the same lobe with a slightly higher and less sharp focus, and 

 hence shows the false reticular image, which will be discussed 

 more accurately and its origin examined into on p. 210 et seq. 

 The distinctness of this false network here is quite striking ; 

 it is also obvious that it must be considerably more prominent, 

 since it appears much darker than the true network does when 

 sharply focussed. Moreover, Photograph XVI. has come out 

 much better than XV. Now, with Photograph XVI. compare 

 Photograph II. of the above-mentioned oil-foam in a correspond- 

 ing focus, from which it is plain that in this respect also there is 

 complete agreement between them. Hence, from the observations 

 that have been adduced, no other conclusion can be drawn than 

 that identical relations are here before us — that is to say, the 

 structure of the protoplasm of j:Tlthalium, like that of the oil- 

 foams, must consist of a more strongly refractile alveolar frame- 

 work, which encloses in its cavities less strongly refracting 

 contents. 



Photograph XVI. permits the corresponding faint structure 

 to be made out much more plainly also in the margin than is 

 the case on Photograph XV. with a sharper focus. This is 

 easily intelligible, since the false reticular image is darker than 

 the true one, and hence stands out more prominently. This 

 circumstance, which in like manner holds good for the oil-lather 

 on Photograph II., may be taken as a sufficiently sure proof that 

 the margin has just the same structure as the interior of the lobe. 



As a further confirmation of what has been stated, I have 

 added two photographs, XVIII. and XIX., at correspondingly 



