October 27, 1911] 



SCIENCE 



575 



The results on the filtrates from peptic di- 

 gestion are corrected in each case for the 

 •weight of magnesium pyrophosphate (9.0 mg.) 

 in the pepsin solution used. In neither experi- 

 ment was there any considerable phosphorus 

 in the sperm used; and it was furthermore as- 

 sumed that the larger part of the latter re- 

 mained in the supernatant sea-water after the 

 eggs had settled. It was practically impossible, 

 howeyer, to run control determinations on the 

 supernatant sea-water because the large 

 amount of salts in each case — over 30 grama 

 — made it exceedingly difficult to carry out 

 the preliminary digestion with sulphuric acid. 



It will be seen that the relative phosphorus 

 partition runs parallel in the two experiments ; 

 that there is not a significant difference in 

 alcohol-soluble (lecithin?) phosphorus or 

 phosphorus in the peptic residues (nuclein?) 

 between the 2-4 cell stage and that of the 

 early blastula. It seems justifiable, therefore, 

 to conclude that under the present experi- 

 mental conditions there is during early cleav- 

 age of the echinoderm egg no evidence of a 

 chemical synthesis of nuclear material from 

 alcohol-soluble substances in the cytoplasm. 



These results, it is emphasized, are referable 

 only to segmentations in an holoblastic egg 

 prior to the possible ingestion of nuclein-con- 

 taining food material from the sea-water. As 

 to just what substances aid in the undoubted 

 increase of total mass of morphologic nuclear 

 substance — not to be confused with the spe- 

 cific substance, nuclein, which, as has just 

 been shown, does not increase — as cleavage 

 proceeds, there may here be mentioned only 

 the possibility that the phenomena of stream- 

 ing cause a morphologic or mechanical aggre- 

 gate of chromatin-like material originally in 

 the cytoplasm with nuclear chromatin during 

 or following mitosis. A number of investiga- 



tions on the distributed nucleus, quoted by 

 Professor E. B. Wilson," form an interesting 

 commentary on the possibility just men- 

 tioned : " Balbiani, Gruber, Maupas and others 

 have described various Infusoria (Urostyla, 

 Trachelocerca, Holosticha, Uroleptus), as well 

 as some rhizopods (Pelomyxa), in which the 

 body contains very numerous minute chroma- 

 tin granules of ' nuclei,' which Gruber showed 

 to multiply by division. Balbiani long since 

 showed that in Urostyla these bodies become 

 concentrated toward the center of the cell at 

 the time of division and Bergh demonstrated 

 that they then fuse to form a macro-nucleui 

 of the usual type that elongates, assumes a 

 fibrillar structure and divides by fission. 

 After division of the cell-body the macro- 

 nucleus again fragments into minute, scat- 

 tered granules, which in this case certainly 

 represent a distributed nucleus. In the 

 flagellate Tetramitus Calkins likewise finds 

 numerous scattered chromatin granules, which 

 at the time of division become aggregated 

 into a single dividing mass; while in other 

 forms the mass (nucleus) persists as such 

 without {Trachelomonas, Lagenella, Ghilo- 

 monas) or with (Euglena, Synura) a sur- 

 rounding membrane." 



Of significance also in this connection is 

 Tennent's' observation that in eggs of 

 Arbacia fertilized with Moira sperm when 

 " the daughter nuclei are in the resting con- 

 dition succeeding the first division, the cyto- 

 plasm contains many deeply staining rods. 

 The nucleus at this time does not take the 

 chromatin stain and appears like an empty 

 vesicular structure. In eggs, of the same lot 

 and on the same slides, in which the fibers of 

 the second amphiaster have begun to form, 

 the nucleus again takes the stain and shows 

 the chromatic net, while the cytoplasm is seen 

 to be free from the bodies described." 



It seems possible to attack this problem of 

 nuclein synthesis from another angle, namely, 

 by comparing the ratio of purin nitrogen to 



" Wilson, ' ' The Cell in Development and In- 

 heritance, ' ' p. 40. New York, 1902. 



' Tennent, Biological Bulletin, Vol. 15, p. 127. 

 1908. 



