1906.] Life-history of Adelea ovata, Aime Schneider. 159 



itself into a stellate mass of chromatin. Hence the highly-characteristic 

 figure of a microgametocyte containing four star-shaped nuclei is presented (8). 

 The stars finally become rounded off (9) — the spherical nuclei so formed 

 afterwards elongating to form the miorogametes, which apparently consist 

 entirely of chromatin (" chromatozoites ") (10 — 11). Many of the micro- 

 gametes enclose a clear space resembling the vacuole described by Schaudinn 

 in Goccidium schubergi. A mature microgamete is shown on a larger scale 

 in text-fig. 2 (12). 



It will be seen from the foregoing that my account of the formation of the 

 male gametes differs considerably from that of previous writers. 



It now becomes an interesting point to determine whether a similar 

 chromidial condition occurs at any period in the life-history of the female 

 forms. So far, I have been unable to reach any satisfactory conclusion with 

 regard to this. However, the following observations seem worth recording 

 in this connection : — 



(a) A single instance has occurred in which the individuals of a group of 

 macromerozoites were found to have their nuclei in a chromidial condition 

 (see Plate 3, fig. 6). 



(b) Since the stellate nuclei of the microgametocyte are formed by 

 synthesis from chromidia, it is possible that the stellate nuclei of the macro- 

 schizont may have a similar origin. Although, up to the present, I have not 

 been able to demonstrate that this is the case, nevertheless, 1 think that the 

 macroschizont, of which fig. 5, Plate 3, is an exact copy, probably shows a 

 stage in which neuclei are being synthesised by the concentration of 

 chromidia at various points. It should be noticed that a considerable 

 quantity of chromatin is scattered through the cytoplasm. I am, of course, 

 ready to admit that this may be quite a wrong interpretation of the 

 appearances. Possibly they are due to degenerative changes. Nevertheless, 

 the phenomenon of chromidia-formation has assumed such importance, owing 

 to recent work in other groups of the Protozoa, that I believe the conditions 

 described may be found to be not altogether insignificant. 



Chromidia. — So many new facts regarding chromidial structures have 

 recently come to light, and so little notice has been taken of them in 

 England, that I think a few words on chromidia in general may not be out 

 of place here. As it is obviously impossible to treat the subject fully in the 

 present paper, I have given a short list of papers bearing on the subject in 

 the literature list (B) at the end ; for a more detailed list of references 

 I refer the reader to the writings of Hertwig [21] and Goldschmidt [18, 19]. 



The conception of chromidia was first formulated by Kichard Hertwig in 

 1902 [20], and resulted from his observations on Actinosphcerium, Arcella, etc. 



