Febeuaey 4, 1916] 



SCIENCE 



171 



Foster failed to read and consequently does 

 not cite along with the other theories advanced 

 as to the origin of the polyradiate cestodes, 

 the theory ofFered by us in the article previ- 

 ously cited, namely that the polyradiate ces- 

 todes do not represent distinct species or 

 genera which necessarily originate from and in 

 turn give rise to onchospheres with super- 

 numerary hooks and cysticerci with an excess- 

 ive number of suckers but may arise from 

 double embryos produced by the partial sepa- 

 ration of early blastomeres and not by the 

 fusion of normal embryos. 



In the light of a large amount of data both 

 in the case of natural and experimentally pro- 

 duced twin embryos and adults of a large 

 munber of animals which shows that the indi- 

 viduals may be joined in various ways and de- 

 grees, our theory as to the origin of the poly- 

 radiate cestodes seems the most logical of 

 those offered. 



Franklin D. Baeker 



The University of Nebraska 



AN ORGANIC OOLITE FROM THE ORDOVICIAN 



lIiCROSCOPic examination of a siliceous 

 oolite from the so-called transition bed be- 

 tween the Prairie du Chien dolomite and St. 

 Croix sandstone at McGregor, Iowa, shows the 

 oolite grains to possess undoubted organic 

 structures of the algal type. The matrix of 

 the oolite grains is dolomitic, and many of the 

 original grains themselves have been partly or 

 wholly changed to dolomite with obliteration 

 of structure, prior to silification. 



The grains range from .1 mm. to 1.13 mm. 

 in diameter, and, when well preserved, show 

 good concentric and radial structure in addi- 

 tion to the minute sinuous fibers similar to 

 those which characterize the Girvanella type 

 of calcareous algs. These fibers have an aver- 

 age diameter of about .015 mm. Typically the 

 well-preserved grains consist of an inner struc- 

 tureless nucleus, followed by an intermediate 

 band showing radial structure, and this again 

 by an outer band bearing the sinuous fibers. 

 In some instances, however, the two outer 

 bands grade gradually into each other without 

 any distinct line of demarcation. 



In view of the present controversy regard- 

 ing the origin of oolite, it is believed that this 

 occirrrence merits more than passing notice. 



Francis M. Van Tuyl 

 University of Illinois 



USE OF C.G.S. UNITS 



In Science of December 24, page 904, Pro- 

 fessor Kent has been good enough to review 

 the various points raised in the discussion con- 

 cerning the fundamental equation of dynamics. 

 As space is limited and the discussion has 

 been prolonged, the pedagogic difficulty in the 

 definition of the dyne may be passed over for 

 the present. Whether there is real difficulty 

 in expressing certain derived units because of 

 the use of exponents is open to argument. The 

 cent is a serviceable unit notwithstanding that 

 some financial transactions run. up to the 

 millions. 



Of more importance however is Professor 

 Kent's statement : 



Of course it is not difl&eult for one who is en- 

 gaged constantly in the use of the C.G.S. system 

 and who during that year has had no occasion to 

 use the old units, to break away from them, but it 

 is not only difficult but impossible, for a hundred 

 million people who are constantly using the old 

 units to break away from them. 



Has he not here overlooked the fact that of 

 the three fundamental units, centimeter, gram 

 and second, one at least, the unit of time, is 

 constantly used by more than a hundred mill- 

 ion people; and of the three concepts, it is 

 perhaps the most difficult. Are not most scien- 

 tific men to-day in all countries using C.G.S. 

 units and their derivatives? Is not the kilo- 

 meter more widely used than the mile ; and has 

 not the kilogram come into very general use? 



Alexander McAdie 



the first secretary of agriculture 

 To THE Editor op Science: I wish to cor- 

 rect a misstatement which occurred in my 

 article on " Botany in Relation to American 

 Agriculture," published in Science, January 7. 

 In this article I stated that J. M. Rusk was the 



