258 



SCIENCE. 



[N. S. Vol. XVII. No. 424. 



genetically related. The homologous 

 theory, based upon (1) the alga-like pro- 

 thallium of certain ferns, together with 

 (2) apospory and apogamy. The objec- 

 tions are (1) the alga-like protonema is 

 almost certainly of secondary origin; (2) 

 apospory and apogamy are readily ex- 

 plicable in other theories. The most prim- 

 itive ferns have the least alga-like gameto- 

 phytes. The numerous resemblances in 

 both gametophyte and sporophyte point to 

 a common origin for bryophytes and 

 pteridophytes. Gametophytes are always 

 aquatic: sporophytes are distinctly terres- 

 trial structures. The evolution of the 

 sporophyte is demonstrated by a series of 

 liverworts. The sporophyte of bryophytes 

 culminates in Polytrichum, and Anthoceros. 

 The sporogenous function becomes subordi- 

 nate and vegetative tissues become highly 

 developed. The uniformity in spore pro- 

 duction is one of the strongest arguments 

 for the common origin of arehegoniates. 

 Ajithoceros resembles most closely the 

 hypothetical primitive pteridophyte. The 

 sporophytes of bryophytes and pterido- 

 phytes show many points of agreement, be- 

 sides being an asexual generation derived 

 from the oospore. Those resemblances 

 probably represent true homologies. Ob- 

 jections to considering apogamy as a re- 

 version are that apogamy occurs almost 

 always under abnormal conditions, and in 

 highly variable and specialized forms. 

 Lang's hypothesis of the origin of the 

 sporophyte is not sustained by the actual 

 behavior of the gametophyte exposed to 

 the assumed conditions, shown in various 

 California liverworts and ferns. Coulter's 

 theory as to the importance of photosyn- 

 thesis in determining the origin of the 

 leafy sporophyte is not impaired by the 

 facts. The development of special green 

 organs is not necessarily associated with 

 terrestrial plants. Apospory and apogamy 



are analogous to adventitious budding. 

 The water supply is the prime factor in the 

 development of the sporophyte. 



Specific Differences in the Wood of Elm 

 Trees: W. J. Beal, Agricultural College, 

 Mich. 



The wood must be examined from a num- 

 ber of trees of any one species and from 

 several places in each tree. The most re- 

 liable differences may not be the same in 

 all genera. In elms, the number of rows 

 and the size of open duets, the thickness of 

 the cell walls and the proportions of the 

 medullary rays, are all important in de- 

 termining the species. 



Some Undescribed Structures in Synchy- 

 trium decipiens: F. L. Stevens, West 

 Raleigh, N. C. 



Several structures of problematic func- 

 tion in the nucleus and cytoplasm of the 

 Synchytrium cell are described and fig- 

 ured. They are developed in connection 

 with nuclear division, although their en- 

 tire divergence from any previously de- 

 scribed cytological structure renders an 

 attempt at exact interpretation hazardous. 

 (Illustrated by a plate and lantern slide.) 



On the Manipulation of Sections of Leaf 

 Cuticle: S. M. Bain, University of Ten- 

 nessee, Knoxville, Tenn. 

 The author outlines his experience in 

 handling leaf sections with special object 

 of determining thickness of cuticle. His 

 method is to imbed in paraffin, cut with 

 blade of microtome Imife in slanting posi- 

 tion and unroll scrolls on drop of distilled 

 water on slide. Preparations are then set 

 aside and water is allowed to evaporate at 

 room temperature. The sections are thus 

 attached by simple adhesion to the glass, 

 the Avhole process being a modification of 

 the method of Nussbaum. Where many 



