Heredity and its Bearings on Atavism. 129 
retina of the Salamander, in the alimentary canal of 
the same animal, during the early development of the 
chick, ete. 
(2) On the staining reactions of nuclei and nucleoli 
during the various phases of cell-life, as seen in the ac- 
companying table. 
Cell. Nucleus. | Nucleolus. 
| 
| | 
During ‘‘rest,” 7.e., not dividing, Blue. - Red. 
During division, . P : ; Red. Colourless, 
During senescence, . : : Red. Red, 
In the ovum, : 3 : ; Blue-red. Red. 
In the spermatozoon, . : ; Blue. Not demonstrable. 
In fungi, . ; , : : Red. (?) 
The following explanation is offered: “We must suppose 
that the new material which is first conveyed to the nucleus 
will take on a blue stain, and that this cyanophilous substance 
is converted in the nucleus into an erythrophilous material, 
which latter is then carried to the nucleolus, because, during 
senescence, division and other conditions (at maturity of 
the ovum), when the cell may be supposed to be less 
actively assimilating food-materials from without, we have, 
invariably, a red coloration taken on by the nuclear chromatin. 
This supposition would also explain why the spermatozoon, 
owing to its great activity, is not able to lay up a store of 
elaborated material, and therefore why it should stain blue; 
1 Differential nucleolar staining was first put on record by Guignard in 
1885 (Ann. Sci. Nat., sér. 6, t. xx., p. 318). Flemming demonstrated this 
fact, however, in 1884 at the Copenhagen Medical Congress, as he states in 
his latest paper: Neue Beitriige z. Kennt. d. Zelle, 24th April 1891 (Arch. 
Mikr. Anat., xxxvii., p. 697); vide also Hermann in April 1889 (Arch. Mikr. 
Anat., xxxiv., p. 60); and G. Mann’s paper, January 1891 (Trans. Bot. Soc. 
Edin.). L. Auerbach first pointed out the differences between the nuclei 
of male and female reproductive organs in Cyprinus, Hsox, Triton, Rana, 
Lacerta, and Gallus—S. B. K. Preuss. Akad. Wiss., 1891, p. 713. F. Rosen 
confirmed Auerbach’s observations for monocotyledonous plants, and also 
pointed out the staining reactions of the nuclei in fungi. Paul Schott- 
linder confirmed them for Cryptogams (Bericht. d. Deutsch. Bot. Gesell., 
1892, p. 27). 
VOL. XII. I 
