278 H. LYNDHURST DUKE. 



Discussion of Somk Spkcial Points in the Life-Cycle. 



In the description of the trophozoite mention has been 

 made of the traces of further segmentation shown occasionally 

 at the posterior end of the deutometrite in Metamera 

 schubergi. 'J'he presence of segmentation in some gre- 

 garines, apart fiom the three fundamental divisions of the 

 body, is a well-established fact, Leger (12) having described 

 a form, Tasniocy stis, where this phenomenon is so well 

 marked as to make the animal resemble a small cestode. 

 Porospora (13) also shows a segmentation, which, however, 

 appears to be somewhat different in nature, as the animal is 

 said to be capable of obliterating its segments merely by 

 stretching itself out during movement. 



In Metamera schubergi the segmentation is always 

 confined to the posterior end of the deutomerite, and is not 

 constantly present. In their full development these posterior 

 septa appear in every way as definite as those of the anterior 

 part of the gregarine; but in some animals, on the contrary, 

 it requires the most careful focussing to demonstrate their 

 existence. I am unable to explain the significance of these 

 septa; whether they mark a certain period in the life-cycle or 

 whether they are due to some form of plasmolysis I cannot 

 say. IMiey are, however, sufficiently often present to form a 

 striking feature of this gregai'ine. 



As regards the explanation of the phenomena shown in the 

 division of the nucleus, it is difficult to discover anything of 

 the nature of a precedent in the current description of this 

 stage. The vacuoles described by Cuenot (6), Prowazek (16), 

 and others, in close proximity to the sporout nucleus, or by 

 Siedlecki (18) within the latter, have not been seen in 

 Metamera schubergi. From the proximity of the com- 

 mencing- achromatic mass to the actively disintegrating 

 karyosome, I suggest that this latter body supplies material 

 — more or less, it is impossible to say — which will assist in 

 the formation of the two daughter-nuclei. Another point, to 



