A genetic study of paramecium caudatum in pure lines through an interval of experimentally induced monster formation
✍ Scribed by De Garis, Charles F.
- Publisher
- John Wiley and Sons
- Year
- 1927
- Tongue
- English
- Weight
- 583 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0022-104X
No coin nor oath required. For personal study only.
✦ Synopsis
The occurrence of monstrous forms in paramecium has been mentioned by a number of observers, but has been studied in detail by very few. Simpson ( '01) found a doublemonster "composed of two full-grown Paramecia with organic union" between the parts. This monster lived for seven days, during which time both anterior and posterior components gave rise to daughter-cells of 'good average size.' The experimental production of monsters in paramecium has been effected by Balbiani ('93), Calkins ('ll), and Peebles ( '12), as the occasional result of transverse cutting at various levels. Such monsters are evidently not comparable to those dealt with in the present report, if one may judge from the following statement of Calkins : "Free cells, complete in all respects, may be given off from the protoplasm of a monster. These may live for days and may even divide, but vitality is weak and they invariably die."
The genetic aspect of the question was introduced by Jennings ( '08), who studied a great variety of distorted and monstrous forms in paramecium, especially with the view of observing in subsequent generations the fate of newly acquired structures. I n practically all cases he found that such structures were lost through a series of cell divisions, the organisms becoming regulated to typical forms. Stocking 133 THE JOUBN.UI OF EXPERIMENTAL Z O ~I r 0 0 Y . VOL. 49, N O . 1 134 CHARLES F. DE GARIS ('15) found that after conjugation in paramecium numerous and sometimes very gross abnormalities develop, and that the condition, abnormality, was variously passed on from generation to generation.
STATEMENT O F TIIF, PROBLEM
The question arises f o r statistical answer: What is the heritable effect of gross abnormality induced not by conjngation, but by some other experimental means? Does monster formation induced in pure lines of paramecium change certain characters which are definitely known beforehand? The present investigation is directed to this question, and the plan of work is outlined in the following propositions: