512 



SCIENCE 



[N. S. Vol. XXXI. No. 796 



per unit of time — about a thirty-milliontli part 

 each year. This can not be precisely true, but 

 I think it must be a better approximation 

 than the hypothesis that this area has under- 

 gone no diminution at all. The results may 

 err in either direction. Thus the rate of dim- 

 inution may fluctuate; if it is now above the 

 average the exponential relation would give 

 too low a value for the earth's age, and vice 

 versa. Whether the rate is actually above or 

 below the average we have no means of dis- 

 covering. Again it is wholly improbable that 

 either intensity of decomposition or the aver- 

 age yield of sodium per square kilometer of 

 sodiferous rocks has always been the same, 

 and this yield may now exceed the mean or 

 fall short of it. 



It appears that Mr. Joly's linear relation 

 between oceanic sodium and its increment 

 must lead to an excessive estimate of the 

 earth's age, at least when the increment is 

 duly determined. Thus that method assigns 

 a limit, a knowledge of which is very valuable 

 as a check on other computations. On the 

 other hand, the ages computed from his data 

 by the exponential expression seem to me sus- 

 piciously low. Various trains of reasoning 

 lead me, at least, to believe that 50 million 

 years is not a maximum but a minimum age; 

 if so and if the exponential hypothesis is ap- 

 plicable then Mr. Joly's datum for the annual 

 sodium increment is too large. 



George F. Becker 



Washington, D. C, 

 February 26, 1910 



BOTANICAL NOTES 

 RECENT STUDIES OF THE FUNGI 



Dr. J. J. Davis's "Fourth Supplementary 

 List of Parasitic Fungi of "Wisconsin " in the 

 Transactions of the Wisconsin Academy of 

 Sciences, Arts and Letters adds many new 

 hosts, many species not hitherto reported, and 

 some species new to science. All of the latter 

 are Fungi Imperfecti. With this may be 

 noticed the same author's " Mycological Nar- 

 rative of a Brief Journey through the Pacific 

 Northwest " (in the same Transactions) in 

 which we are reminded of the itineraries of 



the earlier botanists, like Kalm and Pursch, 

 or even the master traveling botanist, Linne, 

 in which not only are we told of the plants 

 observed and collected, but we are made de- 

 lightfully aware of the botanist himself. Our 

 younger botanists might profitably study the 

 style of the paper before us. 



In these days when all lichens are fungi, 

 we may notice here L. W. Eiddle's " Key to 

 the Species and Principal Varieties of Cla- 

 donia occurring in New England," which 

 appeared in Bhodora for November, 1909. It 

 looks promising, and no doubt will be helpful 

 to students. 



Of quite a dilTerent nature is Professor 

 Atkinson's paper on " Some Problems in the 

 Evolution of the Lower Fungi," published in 

 Annates Mycologici, 1909. It was first de- 

 livered as the presidential address before the 

 Botanical Society of America. In a most 

 ingenious manner the author argues for the 

 origin of the Phycomycetes from the lower 

 unicellular algae such as the Protococcoideae 

 through Chytridiales, to Saprolegniales, etc. 

 He discusses the " degenerative influence of 

 parasitism " and comes to the conclusion that 

 " there seems little in support of the theory." 

 On the contrary, he builds up " a natural 

 series from Chytridiales to the Oomycetes and 

 Zygomycetes, showing progressive evolution of 

 the vegetable body and sexual process." While 

 the paper may not be conclusive, it is sug- 

 gestive and should be read by every student 

 of the lower fungi. 



W. H. Brown, in a note on " Nuclear Phe- 

 nomena in Pyronema confiuens " in the Johns 

 Hopkins University Circular, 1909, points out 

 that " it seems probable that the fusion of 

 the sexual nuclei originally took place in 

 the ascogonium, but later was delayed until 

 some point in the development of the asco- 

 genous hyphae." In this way he suggests a 

 reason for the disappearance of the functional 

 sexual organs in many fungi. 



Here may be mentioned several papers on 

 the economic aspects of certain parasitic 

 fungi ; namely, H. T. Giissow's " Serious 

 Potato Disease occurring in Newfoundland" 

 (Bull. 63, Canadian Dept. Agric), in which a 



