ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 393 



portion of the races in which abnormals were regularly discarded and 

 only normals retained to carry on the race, the abnormal character 

 persistently reappeared. Single lines, derived by fission from a single 

 parent, were divided, by selection, into two or more races differing 

 hereditarily. This was successfully accomplished in twenty-five races : 

 from each of these were isolated two sorts of lines, one quite normal, 

 the other continually producing abnormalities. Selection was effective 

 even when begun with the progeny of a single individual that had 

 appeared many generations after conjugation. In a race of Paramecium 

 which shows no hereditary abnormalities, conjugation results in the 

 appearance of many lines which are hereditarily abnormal, and others 

 which are normal throughout (Jennings' " production of variation by 

 conjugation "). In the diverse lines descended from the different 

 esconjugants of a conjugating culture, the two lines descended from the 

 two individuals that have conjugated together tend to be alike in 

 respect of normahty or abnormality — that is, the characteristics of the 

 progeny of A are not determined hy the nature of A alone, Init partly 

 also by the fact that A has conjugated with B. 



The paper concludes with a comparison of the genetics of these 

 "abnormalities" in Paramecium with those in other organisms. 



Mitochondria of Balantidium.* — L.Leger and 0. Duboscq describe 

 in E. eJoii'/ation the presence of numerous bacilliform mitochondria, 

 genuine chondrioconts, in the cortical plasma, below the alveolar layer 

 of the ectoplasm. The minute rods are about 3 /j. in length, straight or 

 curved, and divide into two or three segments. In the peristomial 

 region they are very numerous and lie at right angles to the surface. 

 In the median region there are fewer, and most are parallel to the 

 surface. Posteriorly they become more numerous and lie at right 

 angles to the margin. Similar rods were described by Zoja in 1891 in ■ 

 what seems to have been B. entozoon. The endoplasm shows few 

 chondrioconts, but there is fibrillar differentiation and there are 

 corpuscles of paraglycogen and siderophilous spheroplasts. 



Bud-formation in Dendrocometes paradoxus.f — Geoffrey Lapage 

 and J. T. Wadsworth have studied the internal budding of this 

 interesting Acinetarian which is epizoic on the gills of Gaminarus 

 jnihx. Each individual produces a single bud at each reproductive 

 act. The bud is roughly oval and plano-convex in shape, measuring 

 0'06 X 0*04 mm. The convex surface is dorsal and is devoid of cilia. 

 The opposite ventral surface bears numerous long cilia, inserted along 

 four ciliated ridges. This surface, hitherto regarded as fiat, is in reality 

 convex in the outer ciliated area, concave in the centre. The bud has, 

 like tlie parent, three microuuclei. 



Bud-formation begins by a linear dissolution of the parent, which 

 proceeds until a dome-shaped mass of cytoplasm is marked off. This 



* C.Pv. Soc. Biol. Paris, Ixxis. (1916) pp. 46-8 (3 figs.). 



t Quart. Journ. Micr. Sci., Ixi. (1916) pp. 337-82 (2 pis. and 16 figs.). 



Aiig. 16th, 1916 2 E 



