ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 329 



that the cells pass out, the same kind of phenomenon is seen. The cells 

 aggregate into true syncytial masses with pseudopodia. The syncytia 

 fuse into an incrustation, and regeneration occurs. Flagellate chambers 

 appear in great abundance, canals arise as isolated spaces which come 

 into connection with one another ; oscula are developed. The syncytia 

 consist mainly of spheroidal granular cells (amcebocytes or archasocytes), 

 but collar cells and more or less hyaline cells also enter into their com- 

 position. The author also describes the fusion of the larvae of a species 

 of Lissodendoryx, and makes some very interesting general suggestions, 

 e.g. by comparing the behaviour of the dissociated cells of sponges with 

 the plasmodium formation in Mycetozoa and Proteomyxa. The ten- 

 dency to fusion exhibited by two similar sponge-syncytia is probably 

 adaptive. The additional safety from enemies and accidents, accruing 

 from increase in the size of the mass, more than compensates for the 

 reduction in number of the individual masses that start to grow. 

 Experiments show that masses of considerable size are frequently able 

 to withstand conditions that wipe out very small masses. 



Protozoa. 



Minute Structure of Amoeba proteus, Pall.* — S. Awerinzew has 

 investigated the structure of Amoeba by the aid of sections. The 

 protoplasm immediately beneath the outer p:llicle is highly vacuolar, 

 but the vacuoles are very small in comparison to those layers within. 

 Here there is a layer of radially arranged relatively large vacuoles, and 

 within this a central region in which the nucleus lies, and in which the 

 vacuoles increase in size and numbers from its periphery towards the 

 centre. The vacuoles of this central protoplasmic mass are on the whole 

 larger than those of the layer immediately beneath the pellicle. The 

 walls of the vacuoles are beset with granules. The nuclear structure 

 resembles that of the protoplasm. The nuclear vacuoles of the 

 external layer nearly all show chromatin corpuscles, stainable with 

 nuclear stains. Similar corpuscles occur also in the walls of the meshes 

 of the remaining nuclear mass. These, however, appear to be distin- 

 guished by their chemical qualities from the peripheral nuclear granules, 

 and are smaller in size. The appearances of protoplasm and nucleus 

 here described have nothing to do with reproductive processes, but 

 represent a stage in those transformations induced by heightened feeding 

 and the accelerated growth consequent on this. 



Degeneration in Opalina.f — C. C. Dobell describes the degenerative 

 changes undergone by Opalina when the host is starved for some time. 

 It changes form and assumes all sorts of indefinite shapes. These 

 modified Opalina do not divide in the normal manner, but simply con- 

 strict off pieces, which completely lose their cilia and give rise to 

 globules of a substance of high refractivity in their cytoplasm, which are 

 " eosinophile " in character. These globules ultimately run together 

 into large masses within the cell. The chromatin of the nucleus in these 

 atrichous forms becomes massed in granules at the periphery, whilst the 



* Zool. Anzeig., xxxii. (1907) pp. 45-50. 



t Quart. Journ. Micr. Sci., li. (1907) pp. 633-46 (1 pi. and 2 figs.). 



