ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 65 



These two granules subsequently unite. In its divisions the blepharo- 

 plast shows no independent mitotic phenomena. It is not a " kineto- 

 nucleus," and its behaviour does not support the binuclearity hypothesis. 



The anterior flagella are shared, two and one respectively, by the 

 daughter blepharoplasts, and new outgrowths complete the complement 

 of each daughter organism. The chromatic margin of the undulating 

 membrane represents an intra-cytoplasmic posteriorly-directed flagellum. 

 It splits longitudinally to the tip of its projecting end. The undulating 

 membrane below it also splits. The chromatic basal rod is the homo- 

 iogue of the parabasal body of Janicki in Parajmiia and the Tricho- 

 oymphidae. His so-called parabasal in Trichomonas is in reality only 

 the early stage of a new parabasal or chromatic basal rod at mitosis, 

 hence its rarity and transitory nature. At mitosis a new parabasal or 

 chromatic basal rod grows out in the base of one new undulating mem- 

 brane, while the old parabasal lies in the other membrane. 



The new axostyles of the daughter organisms are formed by the 

 jongitudinal splitting of the old. The axostyle is not for support or 

 fixation ; it is a locomotor organ used vigorously in the amoeboid phases. 

 During mitosis the organellge are shifted about a good deal. Plas- 

 motomy is long delayed after nuclear mitosis. The plane of division is 

 longitudinal. Multiple fission occurs as a normal phase of the life-cycle, 

 and results in an eight-nucleate plasmodium or somatella. This dis- 

 integrates into its component members by the successive detachment of 

 single merozoites. This multinueleate plasmodium may point on to 

 Metazoa. J. A. T. 



Chromosome Cycle in Gregarines. — A. Pringle Jameson (Quart. 

 Journ. Micr. Sci., 1920, 64, 207-66, 4 pis.). An account of the life- 

 -cycle of Diplocystis scJmeideri, a parasite of the cockroach, with special 

 reference to the behaviour of the nuclei and chromosomes. The author 

 deals with the life-history as a whole, the spore and the sporozoites, the 

 penetration of the gut-wall and the growth of the parasite therein, the 

 growth in the cavity of the body, the first nuclear division of the adult 

 parasite (gamont), the later nuclear divisions, the peripheral divisions 

 preceding gamete formation, the formation of the gametes, the union 

 of the gametes, the first division (reduction division) of the sporoblast 

 nucleus, the later divisions within the spore. A comparison is made 

 between the nuclear phenomena in Diplocystis and those in other 

 'Gregarines. Special emphasis is laid on three points. 1. In Diplocystis 

 -schneideri a " micronucleus " makes its way inside a nucleolus, giving rise 

 to a " karyosome " composed of two clearly differentiated portions. A 

 similar construction of the karyosome occurs in many other Gregarines, 

 and this raises the question how the entire Gregarine " nucleus " is to 

 be compared with the nucleus of a Metazoan cell. It is probably a 

 much more complex organ, comparable to a nucleus within a nucleus. 

 2. Hitherto, reduction in Gregarines has been sought for in the two 

 nuclear divisions immediately preceding gamete formation. But in none 

 of the so-called " reduction divisions " which have been described has 

 a true reduction been demonstrated. In Diplocystis schneideri the 

 reduction division has been found to be the first division in tne 



