66 THE MYCETOZOA 



These authors suggest that the fusion of nuclei in the young sporangium 

 is a long-deferred karyogamy, separated by the whole of the plasmodium 

 stage, with its many nuclear divisions, from the plastogamy (the fusion of 

 the amoebulae) by which the plasmodium originates. They thus regard 

 the mitosis preceding spore-formation as the one nuclear division in the 

 life-cycle in which the full ("somatic") number of chromosomes is present. 



Jahn (I.e.) and, subsequently, Olive 1 also state that a fusion of nuclei 

 occurs in Ceratiomyxa prior to the formation of the spores. The fusion is 

 followed by four according to Jahn, by two according to Olive, mitotic 

 divisions, and the ripe spore is four-nucleated (not one-nucleated, as in- 

 dicated above (Fig. 18, c)). 



It would thus appear that there are, at any rate, two mitotic divisions 

 before spore-formation in Ceratiomyxa and only one in the Endosporeae. 

 The spores are thus not strictly homologous in the Endosporeae and 

 Exosporeae. That of Ceratiomyxa is more advanced than the spore of the 

 Endosporeae in that at least two mitotic divisions subsequent to karyogamy 

 have occurred (and the four nuclei thus arising are contained in the spore), 

 but it is less advanced in that no cleavage of the protoplasm about the 

 products of division has taken place. 



LITERATURE. 



1. de Bary, A. Die Mycetozoen. Zeits. f. \viss. Zool. vol. x. (1860), p. 88. 



2. Die Mycetozoen. 2 e Auflage, Leipzig, 1864. 



3. Comparative Morphology and Biology of the Fungi, Mycetozoa, and 



Bacteria. Translation. Oxford, Clarendon Press, 1887. 



4. Butschli, 0. Protozoa, Abth. g, Sarcodina. Bronn's Thierreich, Bd. i. 



5. Cienkowski, L. Die Pseudogonidien. Priugsheim's Jahrbiicher, i. p. 371. 



6. Zur Entwickelungsgeschichte der Myxomyceten. Pringsheim's Jahr- 

 biicher, iii. p. 325 (published 1862). 



7. - Das Plasmodium. Ibid. p. 400 (1863). 



8. Beitrage zur Kenntniss der Monaden. Arch. f. mikr. Anat. i. (1865), 



p. 203. 



9. Famintzin, A., and Woronin, M. Ueber zwei neue Formen von Schleimpilzen, 



Ceratium hydnoides, A. and Sch., and C. porioides, A. and Sch. Mem. de 

 1'Acad. Imp. d. Sciences de St. Petersbourg, ser. 7, T. 20, No. 3 (1873). 



10. Greenwood, M., and Saunders, E. E. On the Role of Acid in Protozoan 



Digestion. Journ. of Physiology, xvi. (1894), p. 441. 



11. Jahn, E. Myxomycetenstudien 3. Kerntheilung u. Geisselbildung bei den 



Schwarmern von Stemonitis flaccida, Lister. Ber. d. deutschen botanischeu 

 Gesellschaft, Jahrg. 1904, Bd. xxii. Heft 2. 



12. Krukenberg. Ueber ein peptisches Enzym im Plasmodium der Myxomyceten 



und im Eidotter vom Huhne. Uuters. aus d. physiol. Inst. in Heidel- 

 berg, 1878, ii. p. 273. 



1 " Cytological Studies in Ceratiomyxa," Trans. Wisconsin Academy of Science, 

 Arts, and Letters, vol. xv. (1907), pt. 2, p. 753 ; and "Evidences of Sexual Repro- 

 duction in Slime Moulds," Science (N.S.), vol. xxv. (1907), p. 266. 



