140 THE JOURNAL OF INDIAN BOTANY.
important. Doubtless protoplasm may change from one condition to the other in response to changing conditions.
But protoplasm certainly is not so simple as a simple two-phase colloidal system. The present theory of colloids allows for the possibility of one colloidal system containing other more or less differentiated systems. " The cell must at least be conceived as a complex of such colloidal systems, some possibly simple two-phase systems . . . some polyphase . . ." Such a conception would account for the presence of localized areas in which special processes are carried on. The surface tension membranes between the various constituents would hinder diffusion between the different regions of the cell, would make possible the maintainance of the various structures and organs of the cell which the microscope reveals, and would permit widely diverse processes to go on simultaneously within the same cell.
Genetics and the structure of protoplasm. Some sort of serial arrangement of hereditary factors in the chromosomes theoretically appears best to fit the facts of chromosome reduction and segregation of factors. From a few accurate records of size and volume of chromosomes, and from measure- ments that have been made of the size of various molecules, there appears to be plenty of room in chromosomes for a number of molecules " equal to the most extreme demands of the factorial hypothesis, if each factor can be represented by a single molecule or even a group of molecules."
Winfield Dudgeon.
Mottier, David M. Chondriosomes and the primordia of chloro- plasts and leucoplasis. Annals of Botany XXXI 1 {1918) pp. 91-114.
1 pi.
Chondriosomes (mitochondria) were discovered in plant cells by Meves in 1904. Since then a great deal of research has led to the conclusion that they are very numerous in the cytoplasm ; that they are practically univers- ally present in plant cells ; and that they are almost certainly permanent cell organs, being transmitted from one cell generation to the next along with the cytoplasm. Some have claimed that they become transformed into plastids of various kinds, while others hold that chondriosomes and the bodies which develope into plastids are quite distinct. It has been found that some of the most commonly used killing and fixing reagents, especially acetic acid, des- troy chondriosomes, and this fact probably accounts for their late discovery. Mottier used as a fixing solution
1% chromic acid 17 cc.
2% osmic acid 3 cc.
glacial acetic acid 3 drops
and stained with either a modification of Benda's crystal violet method or iron- alum-haematoxylin. He worked with root tips of Pisurn sativum, Zea mays, and Adiautum pedatum; thalli of Marchantia polymorpha, Anthoceros laevia, and Pallacicinia ; seedlings of Pinus Banksiana ; and stem and leaves of Elodea> canadensis. Pisum proved to be the most satisfactory material for study.
When properly fixed and stained, the meristem cells of the root-tip of Pisum show a large number of small but quite conspicuous bodies of two distinct kinds scattered through the cytoplasm : some are larger, straight or variously bent rods of varying length and thickness ; others are very small granules occurring singly or in chains, or delicate slender
