OCTOBEE 27, 1911] 



SCIENCE 



573 



cells derived from the two distinct species. 

 Between these two extremes there are many 

 intermediate forms. The hybrids arising from 

 the fusion of cells behave very much like sex- 

 ually produced hybrids, even to the number of 

 chromosomes in the hybrid cells. 



Dr. Campbell's studies of the " Embryo- 

 sac of Pandanus " (Ann. Bot., July, 1911) 

 brings out the fact that at the time of fertili- 

 zation of the egg there may be present as many 

 as 64 antipodal nuclei, in addition to the 

 usual egg apparatus at the micropylar end. 

 This he regards as a primitive condition, or 

 in other words as an older type of embryo-sac 

 which has survived to the present. 



The new botanical periodical Zeitschrift 

 fur Botanik (Fischer, Jena), now in its third 

 year, is proving to be a useful addition to the 

 already long list of botanical journals. Its 

 editors are Professors Jost (Strassburg), 

 Oltmanns (Freiburg) and Solms-Laubach 

 (Strassburg). Recent numbers contain 

 papers as follows : " Contributions to our 

 Knowledge of the Laminariaceae " (by Kil- 

 lian), " On the Development of Basidia in 

 Uninucleate Mycelium of Armillaria mellea " 

 (Kniep), "On the Reduction-division in the 

 Zygotes of Spirogyra, and of the Significance 

 of Synapsis " (Trondle) in addition to many 

 brief reviews, and classified titles of new 

 literature. 



Charles E. Bessey 



The University op Nebraska 



SPECIAL ASTICLES 

 phosphorus metabolism during early cleav- 

 age OF THE ECHINODERM EGG' 



In his recent book on artificial partheno- 

 genesis Professor Loeb^ assumes that during 

 cleavage of the ovum there is a progressive 



'■ I am indebted to the Commissioner of Fish- 

 eries, Hon. Geo. M. Bowers, for the facilities 

 afforded; and to the director of the Beaufort 

 Laboratory, Mr. H. D. AUer, for many personal 

 courtesies extended to me during this work. Dr. 

 E. P. Lyon has aided me greatly with suggestive 

 criticism. 



' Loeb, ' ' Die chemische Entwicklungs-erregung 

 des tierischen Eies, " p. 18 ff. Berlin, 1909. 



sjTithesis of nuclear material from constitu- 

 ents of or reserve substances in the cyto- 

 plasm. This assumption is based primarily 

 on the observation of Boveri that following 

 each cell-division there is a growth of the 

 daughter-chromosomes in each resultant cell 

 until their mass is approximately equal in 

 each case to that of the original mother- 

 chromosomes; in other words, the mass of 

 nuclear material increases in a geometric 

 ratio as cleavage progresses. The following 

 observations are also brought forth by Loeb 

 in support of this hypothesis of nuclein 

 synthesis : " Mieseher found that the lecithin 

 content of the blood of the salmon was rela- 

 tively high during spermatogenesis and men- 

 tioned the possibility that lecithin might fur- 

 nish a building material for the nucleinic 

 acid of the spermatozoon head. What is there- 

 fore true of the building of nucleinic acid 

 in the spermatozoon is assuredly true also 

 for the building of nucleinic acid in the egg. 

 Hoppe-Seyler has mentioned the fact that all 

 young, quickly growing tissues contain rela- 

 tively large quantities of lecithin. This is 

 especially true in the case of the ovum. The 

 researches of Kossel have shown, on the other 

 hand, that the yolk of hens' eggs contains no 

 preformed nucleinic acid and the same has 

 been shown to be true for the yolk of silk- 

 worms' eggs by Tichomirow. Since there is 

 in the egg after fertilization a rapid synthesis 

 of nuclear material at the expense of certain 

 constituents of the protoplasm or of the yolk, 

 since the latter is rich in lecithin which dis- 

 appears during nuclein synthesis, it is allow- 

 able to suppose that lecithin supplies part of 

 the material for the nucleinic acid." 



It may be pointed out that this supposed 

 use of lecithin is not consistent with the idea 

 advanced by Overton,' Koch* and others that 

 this substance among other lipoids plays an 

 important role in the limiting membranes of 

 many animal cells. It would seem indeed 

 that as cleavage progresses more rather than 



" Hober, ' ' Physikalische Chepiie der Zelle und 

 der Gewebe, " p. 114. Leipzig, 1902. 



*Koch, Zeit. f. Physiol. Chem., B. 63, S. 442. 

 1909. 



