OF EXPERIMENTAL WORK I93 



NITROGEN 



Nitrogen by weight, times 6.25 is usually assumed to give protein present. 

 Amount. — Of nitrogen in eggs (Ballentine, 1940 a): 

 0.107 rng- nitrogen per mg. dry weight 

 265 mg. dry weight per cm.^ cells 

 58.0 mg. dry weight per 10® cells 

 26.8 mg. nitrogen per cm.' cells 

 5.86 mg. nitrogen per 10* cells. 

 Similar figures have been given by Hutchens, Keltch, Krahl and Clowes (1942) ; 

 they report also 10 % of nitrogen is in the jelly. 



Increase. — In soluble nitrogen on autolysis of unfertilized and fertilized eggs, in 

 acid solution; increase in soluble nitrogen on autolysis of sperm in neutral or alkaline 

 media; about one sixth of soluble nitrogen from autolysed and control eggs is of 

 protein origin (Lyon and Shackell, 1910a). 



Other Species 

 Ephrussi, 1933. Paracentrotus lividus, 10.7% nitrogen dry weight. 

 Gustafson and Hjelte, 1950. P. lividus, amino acid-N. 

 Hultin, 1950C. P. lividus, uptake of **N-labeled ammonia. 

 Wetzel, 1907. P. lividus, 1.6% nitrogen wet weight, 7.2% dry weight. 



NUCLEAR DIVISION WITHOUT CELL DIVISION 



Historical. — First obtained by O. and R. Hertwig in 1887 in Paracentrotus lividus with 

 nicotine, chloral hydrate, etc. In Arbacia punctulata, with salts on fertilized eggs, with 

 NaCl by Loeb (1892). Questioned by Morgan (1893, 1896). Loeb's results were 

 confirmed by Norman (1896) with MgClj, and restated by Loeb (1895b, 1900a). 

 Morgan later (1899) agreed that nuclear division could take place without cell 

 division, but was irregular and accompanied by artificial astropheres. 



Urea. — (R. S. Lillie, 1903). 



Cold. — 0° to 2 °C., then room temperature (Lyon, 1904b). 



Acid. — And alkali (Smith and Clowes, 1924c). 



Carbamates. — (Cornman, 1950 b). 



Nitrous Oxide. — (Haywood, 1953). 



Normally in many fertilized red half-eggs, granular, yolk and pigment quarter- 

 eggs obtained by centrifugal force (E. B. Harvey, 1932, 1940c, 1951, and this Mono- 

 graph). 



For obliteration of cleavage plane, leaving nuclear without cell division see 

 Anaesthetics, Hydrostatic Pressure, Oxygen-Lack. 



Other Species (additional) and General References 



Boveri, 1897. Echinus (Psammechinus) microtuberculatus, pressure and cold. 



Driesch, 1892. Same species, pressure and heat. 



Godlewski, 1908. Same species, COj. 



Korschelt and Heider, 1902, p. 215. General. 



Moore, Roaf, and Whitley, 1905. Echinus esculentus, alkali. 



Polowzow, 1924. P. lividus, alcohol. 



Sugawara, 1943 a, b. S. pulcherrimus, "hatching enzyme", trypsin, pepsin, papayotin, CeClg, 



ageing. 

 Sugiyama, 1938a, b, c. 5. pulcherrimus, Pseudocentrotus depressus, Mespilia globulus etc., egg 



albumen, heparin, hirudin; oxygen consumption. 

 E. B. Wilson, 1901a. Toxopneustes (Lytechinus) variegatus, parthenogenetic eggs with MgCl^. 

 E. B. Wilson, 1901 b. Fertilized eggs with shaking and ether. 

 E. B. Wilson, 1925. The Cell, p. 174. Analysis, separability of factors. 

 Ziegler, 1894. Echinus (Ps.) microtuberculatus, pressure. 



