VARIOUS PHASES OF HJIMAMCEBID^. 581 



Note on the Morphological Significance of the 

 Various Phases of Hsemamoebidse. 



by 



E. Ray Laiikester. 



The discovery of true sexual zygosis in unicellular or- 

 ganisms^ has so great an importance that I have thought it 

 desirable to add a few words to the valuable account given 

 by Messrs. Ross and Fielding-Ould, and to place before the 

 reader some woodcuts illustrating the recent discovery of 

 microgametes and maci'oganaetes in the life-history of Coc- 

 cidiidge, which serve to emphasise and confirm the discovery 

 of MacCallum of sexual zygosis in the Haemamoebse. A very 

 interesting and significant fact is that the microgametes of 

 these Protozoa are neither more nor less than spermatozoa — 

 agreeing with the spermatozoa of higher organisms in form 

 and appearance and in mode of development. It is less 

 remarkable, though significant, that the macrogamete is 

 identical in character with the egg-cell or ovum of higher 

 forms. 



The Coccidiida9 are closely related to the Haemamoebidge. 

 Their sexual history was discovered but very shortly before 

 that of the blood-parasites. 



In the first woodcut (Figs. 1 to 6) is shown in the upper 

 three figures the development of the spermatozoa or micro- 

 gametes of Benedenia ectopia n a, a coccidian parasite 

 in the Cephalopod Octopus. The spermatozoa are seen to 



• The Protozoa in which microgametes and macroganietes were i^nown 

 before the year 1898, viz. Volvox and Vorticellidse, are multicellular cell- 

 c jlonies of which only special cells become developed as gametes. 



