January 29, 1004.] 



SCIENCE. 



175 



ture on the development of the moss arehe- 

 gonium from 1851 to the present. A sum- 

 mary of this literature shows considerable 

 divergence in the opinions and interpreta- 

 tions of the several investigators. The 

 crux of discussion has been in respect to 

 the origin of the members of the axial row, 

 but particularly Avhether the terminal cell 

 (cover cell of liverworts) adds to the row 

 after its first division. The discovery of 

 a mitotic figure in this cell after one cell 

 had been cut off enables the writer to de- 

 cide this question affirmatively. In a sec- 

 ond part of the paper, the author demon- 

 strates the homology of archegonia and 

 antheridia from the standpoint of (a) 

 homology of the organs as indicated in 

 early stages of development ; ( 6 ) homology 

 of the egg and other members of the axial 

 row; (c) the homology of the members of 

 the axial row and sperm mother cells. 

 From certain bisexual organs, and from 

 abnormal or slightly modified forms of 

 both archegonia and antheridia, the au- 

 thor is able to offer support to recent 

 views as to the phylogeny of the archego- 

 nium and to throw light upon the meaning 

 of abnormal forms, and particularly to 

 groups of cells at the apexes of certain 

 archegonia for which up to the present no 

 adequate interpretation has been sug- 

 gested. 



The Enzyme-secreting Cells in the Seed- 

 lings of Zea Mais and Phoenix dactyl- 

 ifera: Howard S. Reed. 

 During the process of germination, the 

 above-named seedlings produce an enzyme 

 for the solution of endosperm. The en- 

 zyme is secreted from a differentiated 

 layer of cells. These cells show continuous 

 morphological changes diiring the time the 

 enzyme is being secreted. When secretion 

 begins the cells of the secreting layer are 

 full of the fine proteid granules, which are 

 thought to be zymogen, because, as secre- 



tion progresses, they constantly disappear. 

 In the early stages of secretion the nuclei 

 of the secreting cells of Zea Mais are 

 found in the basal end of the cell; in the 

 later stages they are in the apical end 

 next the endosperm layers. As secretion 

 progresses, there is a continuous increase 

 in the amount of chromatin in the nuclei 

 of the secreting cells. At the same time 

 the nucleoli decrease in size and staining 

 properties. At the end of the process 

 the protoplasm of the secreting cells 

 breaks down and the products of disinte- 

 gration disappear from sight. 



Discoid Pith in Woody Plants: F. W. Fox- 

 worthy. 



Discoid Pith: Any pith which is inter- 

 rupted at frequent and tolerably regular 

 intervals by transverse partitions dividing 

 the pith up into a series of chambers. 

 These partitions, disks, diaphragms, plates 

 or lamellfe, as they are variously called, 

 may be composed either of thick-walled or 

 of thin-walled cells, and the spaces between 

 the disfe may be empty or filled with cel- 

 lular tissue. Thus, M. Gris classifies discoid 

 pith as: (1) Heterogeneous continuous 

 diaphragmatic, when the pith is- contin- 

 uous between the disks, and (2) hetercge- 

 neous discontinuous diaphragmatic, when 

 the pith is not continiious between the 

 disks, but the interspaces filled with air. 

 The first type of pith is found in Lirioden- 

 dron, Magnolia species, Asimina, Nyssa, 

 etc., and the cells forming the disks are 

 verj thick-walled and heavily lignified, 

 while the cells forming the interspaces are 

 small, very thin-walled and empty. The 

 second type . is found in Juglans, Ptero- 

 carya, Celtis, Halesia, Forsythia viridis- 

 sima, Jasminuni species, Paulownia, etc., 

 and the cells forming the disks are thin- 

 walled, empty and often shrunken. Dis- 

 coid pith seems to be of taxonomic impor- 

 tance for generic distinctions in some 



