Morphologie etc. — Varietäten, etc. 3 



the poles, but more usually they divide their substance into a few 

 continuous Strands, to reassemble as disks at the poles of the ana- 

 phase. As the disks approach the poles, they appear to blend with 

 siroilar disks, apparently evolved from cytoplasm. 



Each daughter disk thus arising upon fixation consists of a 

 series ot" about four rows of tetrahedral masses. In living material 

 the same appears as a translucent rim surrounding a less dense 

 interior. The translucent rim becomes the nuclar plasm, while the 

 central body takes shape within the less dense interior. 



Spirogyra may be characterized as having chromatic substance 

 of a polymorphous nature (disk or spireme). As regards the Consti- 

 tution and behavior of the nucleolus, Spirogyra need not be placed 

 in a different category from the remainder of the green algae or 

 from that of higher plants. Jongmans. 



East, E. M., Inheritance in crosses between Nicotiana Längs- 

 dorffii a.nd Nicotiana alata, (Genetics. I. p. 311—333. 1916.) 



Of the very few species crosses in the genus Nicotiana between 

 species whose Status would not be questioned by taxonomists, the 

 one showing the most perfect fertility is described by the writer in 

 this paper. It is the cross between Nicotiana Langsdorffii Weinm. 

 and Nicotiana alata Lk. and O., species so different from each 

 other, that they were placed in different sections of that genus, 

 those of Rustica and of Petuniodes. From a great many obser- 

 vations and measurements, obtained at plants of F^, Fj and Fg 

 about inheritance of pollen color and of flower color, fertility of 

 the hybrids, height, rapidity of growth, leaves, corolla length, in 

 both reciprocal crosses, the following conclusions may be drawn: 

 It does not matter which way the cross was made. The Fj-popu- 

 lations are as uniform as the parents. The Fg-generations are 

 nearly three times as variable as the F^-generations. Individuais 

 reproducing the smaller species were found in the Fogeneration. 

 Certain of these Fa-individuals reproduced N, Langsdorffii popu- 

 lations in the Fg-generation. No Fa-individuals reproducing N. alata 

 grandiflora were found, but Fg-plants approaching such a type 

 were produced. Galtonian regression occurred, but selected extremes 

 regressed no more than those deviating moderately from the 

 parental mean. Individuais from the same point on the Fo-curve 

 showed different variabilities in Fg. The variabilities of Fg-families 

 were invariably smaller than those of Fg families. These conclusions 

 are based upon corolla length measurements but apparently are 

 true for other characters, except that in other characlers N. alata 

 grandiflora types were reproduced. Mendelian inheritance of corolla 

 color and pollen color is shown. Mendelian inheritance seems to 

 be the only logical Interpretation of the other phenomena. 



M. J. Sirks (Wageningen). 



East, E. M„ Studies in size inheritance in Nicotiana. 

 (Genetics. I. p. 164—176. 1916.) 



The data considered in this paper were obtained by measuring 

 the length of corolla in a cross between two varieties of Nicotiana 

 longiflora Cav. Both of these varieties used as parents might 

 reasonably be supposed to be homozygous in most of their characters 

 for they are generally selfpollinated naturally. Whether either or 

 both of them had been self-pollinated artificially before the writer 



