442 



SCIENCE 



[N. S. Vol. XXXIV. No. 875 



phyllites, Neuropieris, Alethopteris, Megalop- 

 teris, Pecopterisj Whittleseya and Sigillaria. 

 David White 



PROFESSOR PUNNETt's ERROR 



In Professor Punnett's admirable little 

 book, entitled " Mendelism," there occurs an 

 error of definition that ought not to go un- 

 noticed. This error, which runs through the 

 whole book, begins on page 2, where may be 

 found this statement : " Among animals the 

 female contributes the ovum and the male the 

 spermatozoon; among plants the correspond- 

 ing cells are the ovules and pollen grains." 



The last half of the quoted sentence con- 

 tains three distinct errors: (1) Half of the 

 plant kingdom possesses no pollen grains nor 

 ovules, yet its members have parts that corre- 

 spond with the ova and spermatozoa of ani- 

 mals ; (2) the ovules and pollen grains are not 

 cells but each is a cell complex; (3) it is a 

 gross mistake to regard the pollen grains and 

 ovules of plants as corresponding with the 

 spermatozoa and ova of animals. 



The first two mistakes might be passed 

 over; but the third, in a book that is written 

 for the reading public, is unfortunate and 

 should be corrected in the next edition. The 

 pollen grain is multicellular and the ovule is 

 multicellular. The genetic cells of higher 

 plants are produced in these bodies. It is as 

 correct to call the testis of an animal a gamete 

 as to call a pollen grain a gamete. The ter- 

 minology of the genetic cells in plants need 

 offer no difficulty to the zoologist. If he will 

 consult the literature, or his botanical friends, 

 he will find that, besides using the term 

 gamete for the conjugating cells of both 

 plants and animals, he may use ovum and 

 spermatozoon for plants as well as for ani- 

 mals. P. C. Newcombe 



PHENOMENA OF FORKED LIGHTNING 



As pointed out in a recent paper in Science, 

 September 1, the negative end of a lightning 

 discharge is forked. When visible we call it 

 forked lightning. When such a system of 

 drainage channels penetrates a shower of nega- 



tively charged drops, great differences in po- 

 tential between drops not far removed from 

 each other must be created. Before the flash 

 the drops have approximately equal potentials. 

 They then repel each other. Drops having 

 radii of one mm. only need to be charged to a 

 potential of 0.0031 volt in order that their re- 

 pulsion for each other may balance their 

 gravitational attraction. 



As soon as the flash occurs these drops at- 

 tract each other. They coalesce, and a brief 

 dash of large drops of rain follows. 



Francis E. Nipi-ier 



SCIENTIFIC BOOKS 

 A Study of Ghiriquian Antiquities. By 

 George Grant MagCurdy. Memoirs of the 

 Connecticut Academy of Arts and Sciences, 

 Vol. III., March, 1911. New Haven, Conn. 

 Pp. 249, 384 text figures, 49 plates. 

 In a beautiful volume Dr. MacCurdy has 

 given us the fruits of a long and patient in- 

 vestigation of the excellent collection of an- 

 tiquities from Chiriqui in the Museum of 

 Yale University. Not too much praise can be 

 given to the painstaking examination and clear 

 description of the long series of specimens, to 

 the careful grouping of the material, which 

 makes it possible for the student to master the 

 wealth of new material with comparative ease. 

 The author's descrijjtion is about the same as 

 that given by Holmes, but with a few modifi- 

 cations in terminology and grouping. To- 

 gether with Professor Putnam's paper on con- 

 ventionalism in ancient American art, and 

 Professor Holmes's earlier description of an- 

 cient art of the province of Chiriqui, we have 

 here material that needs only the additional re- 

 searches of the field investigator to give us a 

 clear picture of the archeology of a part of the 

 Isthmian region. It is fortunate that, for a 

 comparison of cultural types, the archeologist 

 has at his disposal the two careful investiga- 

 tions by Dr. Hartman on the eastern and west- 

 ern parts of Costa Eica. 



The illustrations in Dr. MacCurdy's volume 

 are of the excellence of all the work of Mr. 

 EudoK W^eber, whose illustrations of the pub- 

 lications of the Heye Expedition and for- 



