NO. 9 RESEARCHES OF JOSEPH JACKSON LISTER HERON-ALLEN 7 



rounded spheres, some 50 fi in diameter, whose center consists of 

 clear granular protoplasm (in which I thought I detected a radiate 

 arrangement) the peripheral part being dark with the coarse brown 

 granules/ 



In some cases part of the protoplasm remains in the terminal 

 chambers of the shell and divides into spheres in this position. This, 

 however, is not usual. 



The spheres form at first a compact mass. Shortly, each becomes 

 surrounded by a close felt of very delicate anastomosing pseudopodia, 

 which when seen with a simple lens has the appearance of a mass of 

 white granules ' and I supposed at first that a deposit of lime granules 

 had taken place about the group of spheres. They gradually draw 

 apart from one another, so that each can be seen as a distinctly iso- 

 lated mass. 



I have killed and stained a number of specimens at different stages 

 of this process. Those in the stage before the protoplasm has left the 

 shell, as well as those at the beginning of the later stage, have the 

 central chambers still filled with protoplasm. In all these specimens 

 it is obvious that it is a uiicrosphcric individual that is undergoing 

 the process. Again, the specimens mentioned above which, having 

 shown a '* premonitory halo," returned to the vegetative condition, on 

 being removed to a cover-slip, are found on being decalcified and 

 stained, to belong also to the uiicrosphcric form. Altogether I sup- 

 pose I have some 15 specimens whose central chambers are still filled 

 with protoplasm and hence furnished evidence as to the form to which 

 they belong. 



In a batch of specimens of Polystomella (some 200-odd) megalo- 

 spheric and microspheric specimens w-ere nine to one. This is good 

 evidence that the reproductive phase I am dealing with is that of the 

 microspheric form. 



The specimens killed in the first stage present, when stained, the 

 appearance I have often seen, the many nuclei being of irregular 

 shapes, and surrounded by numbers of " stained strands." In some 

 cases no definite nuclei can be detected, and only few of the strands. 

 When nuclei are present they do not extend into the terminal chambers 

 of the shells. 



In specimens whose protoplasm has begun to emerge, faintly stained 

 round nuclei 10 /i, in diameter are found in the clear protoplasm 

 of the terminal chambers, while the innermost protoplasm still has 

 the diffused flush and contains strands of stained matter. 



2 : 40 p. m. 



■4: 30 p.m. 



