114 



We must now refer to the brilliant work done by Schaudinn 

 in the elucidation of this interesting biological problem, who 

 quite independently of Lister has been engaged on the same 

 investigations, and by a curious coincidence has taken the same 

 species as Lister (Polystomella crispa) as his principal type. Not 

 only have these two eminent naturalists been independently led 

 to the same conclusion, but Schaudinn has thrown much additional 

 light on the reproductive phenomena of the Foraminifera.* By 

 the use of very high magnifying powers (up to 2,000 diameters) 

 he has watched the changes that take place in the nuclei during 

 the reproductive process, and are of the greatest interest. In the 

 first place he has never seen a nucleus multiply by constriction, 

 as is frequently the case in some Orders of the Protozoa, but the 

 nucleus passes through a succession of very remarkable and com- 

 plex changes which cannot well be made intelligible without 

 reference to the diagrammatic figures by which his work is 

 illustrated. Stated generally, however, the nucleus when passing 

 into the reproductive stage first develops a granular centre, 

 around which gathers a sphere of droplets like an alveolary 

 border. A process of segregation goes on and a cyst is formed, 

 the inner surface of which is covered by a number of compact 

 spheroidal bodies. When matured, the cyst bursts and the 

 spheroids are distributed throughout the protoplasm of the 

 animal as embryonic nucleoids. 



The next question was to determine the distinctive changes 

 which take place respectively in the megalospheric and micro- 

 spheric forms of propagation. In the case of microspheric 

 generation there develops the cyst-like bodies with included 

 zoospores, as already described. In the crisis of reproduction, 

 the cyst bursts, the corpuscular bodies are set free, and by a rapid 

 circulatory movement, that is set up concurrently in the proto- 

 plasm, they are evenly distributed throughout the mass. At this 

 stage the whole of the protoplasm vacates the shell, forming an 

 irregular mass. The protoplasm then divides into sections of 

 various sizes, each fragment assumes a rounded form, secretes a 

 calcareous test, and this globular test constitutes the primordial 

 chamber of a Polystomella crispa, of the megalospheric form. In 

 these observations two points were established ; first, that the 

 whole of the parent body was used up in the formation of off- 

 spring ; and, secondly, a microspheric individual gave birth to a 

 megalospheric progeny. 



* For particulars of M. Schaudinn's investigations I am chiefly indebted 

 to M. Schlumberger, who in the following two papers has given an excellent 

 resume of Schaudinn's Preliminary Notes, with a reproduction of Schau- 

 dinn's figures. Note sur la Biologie des Foraminiferes. La Plastoqamie 

 dans les Foraminiferes, par Ch. Schlumberger, in La Feuille des Jeunes 

 Nattiralistes, in Mars et Mai, 1896. 



