k Heterotypical Reduction ’ in Somatic Cells . 
801 
Summary. 
i. By treatment with a dilute solution of chloral hydrate the occurrence 
of tetraploid cells may be induced in the young root-tips of pea, bean, and 
Galtonia . 
1 . This condition arises secondarily, and as the result of the dis¬ 
appearance of the achromatic fibres of the cell, under the influence of the 
chloral hydrate. The movement of the split chromosomes to the poles is 
arrested and a single large nucleus arises by their re-fusion to form one 
mass. 
3. Three types of tetraploid cell may result. Such a cell may contain 
(1) two nuclei, (2) an amoeboid or ‘ bridge ’ nucleus, (3) a single nucleus 
of normal shape but abnormal size. 
4. With recovery by the tetraploid nuclei of their normal appearance, 
the cells containing them increase in size till they attain fully twice their 
usual dimensions. 
5. In division, the tetraploid cells give rise (1) to single large figures 
in which it is possible to count twice the normal number of chromosomes, 
(2) to two separate division figures in one cell, (3) to multipolar divisions. 
6. The tetraploid cells gradually disappear from the root-tip. This 
disappearance is probably due to their division into several smaller cells ; 
their fragmentation and absorption, of which process many figures occur ; 
or to their passing over into the permanent tissue and relapsing into in¬ 
activity. 
7. Certain figures occur in the pea remarkably like the heterotype 
reduction-figures seen in sporogenous tissue. These, however, are shown 
to be merely peculiar forms, which result probably from some chemico- 
physical effect of the chloral hydrate upon the chromatin, and which, 
though they resemble the figures characteristic of reproductive cells, have 
in reality no connexion with the process of normal reduction. 
In conclusion, my hearty thanks are due to Professor J. Bretland 
Farmer, under whose direction this work has been carried out. 
Bibliography. 
1. Gerassimow, J. J. : Zur Physiologie der Zelle. Bull. Soc. Imp. Nat. Moscou, 1904, no. 1. 
2. _: Ueber die Grosse des Zellkernes. Beih. Bot. Centralbl., xviii, 1904. 
3. Haecker, V.: Ueber die in malignen Neubildungen auftretenden heterotypischen Teilungsbilder. 
Biol. Centralbl., xxiv, 1904. 
4 _ _ ; Mitosen im Gefolge amitosenahnlicher Vorgange. Anat. Anz., xvii, [900. 
5 Laibach, F.: Zur Frage nach der Individualist der Chromosomen im Pflanzenreich. Beih. 
Bot. Centralbl., xxii, 1907. 
