28G PKOF. ALLMAN ON THE BECENT RESEARCHES 



the central mass. Max Schultze had further m ade the important 

 discovery that the pseudopodia of ActinospTicBrium possess a more 

 complex structure than had been imagined — that they consist 

 of a firmer hyaline strongly refringent axis, surrounded by a soft, 

 granular, mobile layer, in which alone the protoplasmic granule - 

 streams exist. The axis was followed by him through the clear 

 cortical zone of the Ehizopod, as far as the boundary of the 

 darker medullary region, while the soft sarcode by which the axis 

 is surrounded was shown to be a continuation of the cortical zone 

 of the body. 



F. E. Schulze now gives his support to the essential points of 

 an observation made by Grreeif, and maintains with that author 

 that the axis filament of the pseudopodia is not simply a continua- 

 tion of the central sarcode, but that it consists of a firm albuminous 

 " spine," which, passing through the superficial zone, rests upon the 

 periphery of the central sphere by a wedge-shaped extremity. 



In his observations on the development of ActinospTicBrmm , 

 Schulze has been preceded and, to some extent anticipated, by 

 Cienkowski* and by Schneiderf. Schulze records the following 

 phenomena as characterizing the reproductive process in this 

 Khizopod. The medullary region becomes darker, more condensed, 

 and more sharply separated from the cortical region ; the axes of 

 the pseudopodia become indistinct and finally disappear, and the 

 whole of the pseudopodia are withdrawn. The entire animal 

 becomes now enveloped in a clear gelatinous excretion, and within 

 this the body, by a process of binary segmentation, becomes 

 broken up into a multitude of spherical masses, each with its 

 medullary and cortical regions, but in which no distinct alveolar 

 condition is any longer apparent. In each there is a single central 

 nucleus, and the cortical layer, as had been already shown by 

 Schneider, now becomes converted into a firm investment by the 

 deposit of siliceous particles. 



After remaining in this state unchanged during the whole of 

 the winter months, the germs were observed at the beginning of 

 spring to have lost their siliceous covering and to have become 

 converted into minute Actinosphcerice, most of which contained as 

 yet only a single nucleus. With the growth of the young Acti- 

 nospTiceria the nuclei became multiplied and arranged themselves 

 towards the periphery of the medullary region as in the adult 

 animal, thus closing the cycle of development. 



* Archivf. mikr. Anat. vol. i. p. 229. 



t " Zuv Kcnntniss der Eadiolarien," Zeit. f. w. Zool. Bd. xxi. p. 507. 



