March 20, 1914] 



SCIENCE 



439 



that all of the spermatozoa in a single cyst arise 

 from a single spermatogonium. These divisions 

 constitute a period which parallels that in Dytiscus 

 during which one oogonium produces fifteen nurse 

 cells and one oocyte. The germ cell substance in 

 many animals is localized in the unsegmented egg 

 and can be distinguished by the presence of stain- 

 able inclusions which may be named keimbahn-de- 

 terminants. 



The Orientation of the Nuclear Organs in the 

 Electric Motor Cells of Tetronaree and Other 

 Torpedoes: Uleich Dahlgren. (Illustrated 

 with lantern slides.) 



Chromosomes in Opalina : M. M. Metcalf. 



The Physical Changes in Marine Eggs in Fertili- 

 sation: G. L. Kite. (Illustrated with lantern 

 slides.) (Introduced by C. E. MeClung.) 



The Molar Structure of Protoplasm: G. L. Kite. 



(Introduced by C. E. McClung.) 



The conclusions presented in this paper are 

 founded on the dissection of representative cells of 

 widely different types of animals and plants. A 

 detailed investigation of the principal kinds of 

 cells of the frog and rabbit has been made. 



Protoplasm has been found to be composed of 

 gels and sols. With few exceptions resting nuclei 

 are rather rigid gels which contain denser areas. 

 Such areas are frequently arranged in the form of 

 imperfect networks. The cytoplasm is usually in 

 the gel state and may contain globules, granules 

 and fibrils. The globules are completely separated 

 from the imbedding gel, while granules and fibrils 

 grade into the contiguous substance. 



Dividing cells have proved to be of special in- 

 terest. Chromosomes and spindle fibers seem to be 

 incomplete separation products. The changes which 

 result in the separations are at least partially re- 

 versible. Experiments on different kinds of divid- 

 ing cells point unmistakably to the fact that the 

 chromosomes and spindle fibers play a secondary 

 role in indirect cell-division. The optically un- 

 differentiated protoplasm, lying around and be- 

 tween the chromosomes and spindle fibers and in 

 the plane of cleavage, is the portion that is the 

 seat of the active changes that result in cell-di- 

 vision. 



The chief general conclusion from this study is 

 that protoplasm is a one-phased system in molar 

 structure. Dissections of cells under quite satis- 

 factory optical conditions have failed to reveal the 

 contiguous solid and liquid phases that are gener- 

 ally held to be the essential elements of protoplasm. 



GENETICS 



A Male Gynandromorph of Colias (Eurymus) 



Eury theme Showing Dimorphism in the Female 



Color Pattern : John H. Gerould. (Illustrated 

 with lantern slides.) 



Inheritance in Orthoptera: Egbert K. Nabours. 



During five years many types with complex color 

 patterns of Paratettix Bolivar, of the Orthopteran 

 subfamily Tetriginae, have been captured and bred 

 in the greenhouse, for two years at the University 

 of Chicago and three years at the Kansas Agricul- 

 tural College, Manhattan. From these have been 

 segregated through Mendelian analyses about 

 fifteen true breeding types. These true breeding 

 forms have been reeombined to make all the orig- 

 inal hybrid types and many others which have not 

 as yet been found in nature. Ten true breeding 

 types have been tried, and, with one exception, 

 each has been found to pair with each of the 

 others, making as many allelomorphie pairs as 

 there are possible combinations. Some of the cul- 

 tures have been carried to the F, generation, and 

 some of the forms have been bred, in one combina- 

 tion or another, for sixteen generations. The re- 

 sults throughout have been typically Mendelian, 

 except that one form, F. melanothorax (G), when 

 crossed with any other form, produces F, progeny 

 that do not always give gametes alternatively, but 

 seem to give some gametes that represent both pa- 

 rents. For instance a melanothorax (G) — lenco- 

 notus (B) hybrid mated with a leucothorax (C) 

 homozygous form gives CG, BC and BCG progeny. 

 Eeciprocal crosses have invariably given identical 

 results. 



The Effect of Selection Upon Egg Characters in 

 Partheno genetic Lines of Hydatina: A. Frank- 

 lin Shxjll. 



Fifty Generations of Selection in Parthenogenetio 

 Pure Lines of Daphnids: A. M. Banta. 

 Selection experiments in pure parthenogenetic 

 lines of daphnids were reported on. In all eighteen 

 lines were continued under selection for eight gen- 

 erations or longer and eleven for from thirty to 

 fifty generations. The daphnids belong to three 

 species and were originally taken from several 

 different ponds near Cold Spring Harbor. Four- 

 teen of these lines are Daphnia pulex, two belong 

 to another species of Daphnia and two are Simo- 

 cephalus. 



The character used as the basis for selection was 

 purely a physiological one, the daphnids' reaction 

 to light. In the beginning of the experiment the 



