March 7, 1913] 



SCIENCE 



381 



presence in the gas studied. We believe the re- 

 sponse of this seedling furnishes a very delicate 

 means of detecting the presence of ' ' heavy hydro- 

 carbons" in laboratory and greenhouse air, in 

 smoke of all sorts and in furnace gases. 

 The Heat of Absorption of Water in Wood: 

 Frederick Ddnlap, U. S. Department of Agri- 

 culture. 



The heat evolved when water wets dry wood has 

 been studied with the Bunsen ice calorimeter. 

 Oven-dry wood was used; this was sealed in glass 

 to prevent premature wetting. The wood and 

 water were both cooled to 0° C. and brought to- 

 gether at this temperature and the heat evolved 

 was measured. This is large enough to raise the 

 dry wood entering into the reaction from 0° to 

 about 50° C. Under the assumption that the 

 specific heat of wet wood is the sum of the specific 

 heats of the wood and water present in wet wood, 

 its temperature would be raised to about 30° C. 



The substance of wood as distinct from the cavi- 

 ties of the cell lumina is saturated when it has 

 imbibed about 25 per cent, of its weight of water. 

 The first per cent, imbibed produces a relatively 

 great evolution of heat; the twenty -fifth, a rela- 

 tively small evolution of heat, the curve connect- 

 ing the two being convex upward. 



Wood is hygroscopic and its moisture content 

 varies with that of the atmosphere about it. The 

 ' ' working ' ' of wood is due to changes of volume 

 of its substance with changing moisture content. 

 Measures to prevent this "working" aim either 

 to remove the wood from the action of the atmos- 

 phere or to render it insensitive to changes in the 

 atmosphere by destroying its liygroscopicity, at 

 least in part. Experiments whose aim it is to 

 destroy the hygroscopicity of wood are now in 

 progress in the Forest Products Laboratory, and 

 this method will be used in studying the changes 

 produced. 



Artificial Parthenogenesis in Fucus: J. B. Over- 

 ton, University of Wisconsin. 

 The occurrence of natural parthenogenesis has 

 been reported for several species among the Pheeo- 

 phyoese. It is evident that this group shows a 

 strong tendency to develop without fertilization 

 and that natural parthenogenesis may play an 

 important part in the life history of several spe- 

 cies. Although Thuret mentions that unfertilized 

 eggs of Fucus kept for several days become pear- 

 shaped and that a cellulose wall is sometimes 

 present, none of the Fucacese have been described 

 as being able to develop without fertilization. 



While working at the Marine Biological Labo- 

 ratory the past summer, the well-known experi- 

 mental methods of certain animal physiologists, 

 whereby unfertilized eggs of certain animals have 

 been made to develop under the influence of arti- 

 ficial physical and chemical stimuli, were applied 

 to Fucus eggs. In plants used for experiment 

 care was taken to prevent contamination by 

 sperms. That female plants may be made per- 

 fectly sterile by washing in fresh water is shown 

 by the fact that none of the eggs of such steril- 

 ized plants ever developed in the numerous con- 

 trols which were run in connection with the ex- 

 periments. In experimenting, the eggs used at 

 any one time were divided into three lots. One 

 lot was used as a control, another was fertilized 

 and the third was placed for one third minute 

 in a mixture of 50 c.c. of sea-water -f- 3 c.c. 0.1 m 

 acetic or butyric acid. A large number of the 

 eggs treated with these solutions become invested 

 with a cell-wall in about 10 minutes. This wall 

 is exactly similar to the one formed about nor- 

 mally fertilized eggs. The wall is readily seen by 

 plasmolyzing the eggs. After the formation of 

 the membranes, if the eggs are transferred to 

 hypertonic sea-water for 30 minutes and then are 

 brought back into normal sea-water, development 

 continues. Such eggs become pear-shaped, show- 

 ing a rhizoidal papilla, and by next day have 

 cleaved. If the cultures are kept properly aerated, 

 sporelings of about 25 cells develop in the labora- 

 tory, resembling in every respect those grown from 

 fertilized eggs. 



It would appear that the action of the acid in 

 inducing cell-wall formation about unfertilized 

 Fucus eggs is similar to the action which calls 

 forth membrane formation in the animal egg. 

 Considerable evidence exists indicating that the 

 essential condition for the formation of the fer- 

 tilization membrane in such eggs is an increased 

 permeability of the plasma membrane to sub- 

 stances which harden in contact with sea-water. 

 That the first effect of the sperm upon Fucus eggs 

 is to cause cell-wall formation is apparent from 

 the observations of several investigators. 



No attempt was made to grow the sporelings 

 under natural conditions. The methods used by 

 Hoyt and Lewis are suggestive and it seems prob- 

 able that the sporelings produced parthenogen- 

 etically could be grown to sexual maturity, so that 

 the nuclear behavior during oogenesis and sper- 

 matogenesis might be investigated. 



