4 THOS. H. MONTGOMERY jr., 



mitosis as in the Coleoptera; the chromosomes usually divide (and 

 then longitudinally) in metakinesis. Pseudoneuroptera {Calopteryx and 

 Lihellula): 8 to 12 chromosomes, which may be either curved or 

 straight; they segment in the equator of the spindle, or not until 

 they have reached the opposite poles. Panorpa: 14 to 18 chromo- 

 somes which segment at the equator. Diptera {Musca, Syrphus): 

 mitoses as in the Coleoptera, with a splitting of the chromosomes in 

 metakinesis. Hemiptera {Nepa, Aphrophora): the continuous spirem 

 segments into long, parallel loops, or (more rarely) into short rods, 6 

 to 12 in number; in metakinesis they either wander apart from one 

 another, or first divide at the equator, as in fig. 103, "ou qui seraient 

 en voie de subir la division transversale. Mais en tenant compte des 

 observations précédentes, ... il est naturel de l'interpréter dans le 

 sens d'une division longitudinale". Résumé: In ail Arthropoda there 

 is a continuous spirem thread, which segments into long parallel loops, 

 or into shorter elements; these two modes of spirem segmentation are 

 considered characteristic of successive generations. In metakinesis 

 (the commencement of the "seconde phase") there may be either a 

 simple wandering apart ("dislocation") of the chromosomes, or else a 

 division of them in the plane of the equator; this division is longi- 

 tudinal except in Astacus and possibly a few other cases, though he 

 considers it quite probable that the two modes might occur in suc- 

 cessive generations. (In Bacillus alone was he able to follow this 

 longitudinal division ; the chromosomes have in this object at first a 

 rod-like form, fig. 291, appear solid, and their long axis is parallel to 

 that of the spindle. Then a longitudinal clear space arises in each 

 of them, but does not cut their ends, so that they acquire an elongate 

 ring-form, figs. 292, 293. Next a transverse line of division appears, 

 as is shown in figs. 294, 295, and as is borne out by the description : 

 "A ce moment le bâtonnet fait l'impression de porter une croix blanche 

 dont le bras longitudinal représente l'espace hyahn primitif, et le bras 

 transversal la ligne de séparation des fers-à-cheval." This transverse 

 split, so clearly figured and described, is disregarded in the subsequent 

 description, where he assumes a breaking of the ends of the rings in 

 order to prove a longitudinal division ; this appearance of a transverse 

 splitting he pronounces an illusion: "Celui qui n'aurait point aperçu 

 les stades intermédiaires des fig. 293 et 294, serait sans nul doute 

 enclin à se prononcer dans ce sens": but the stages to prove his 

 assumption, which would fall between figs. 293 and 294, are not 

 figured !). 



