THE EFFECTS OF HYPEIITONIC SOLUTIONS. 
475 
the more sensitive E. acutus chromatin to go wrong when it 
enters the cytoplasm of the more resistant E. esculentus, 
anil yet this is not the case. 
The proof of the hypothesis^ here put forward tentatively, 
would lie in the demonstration of the fact that the perme- 
ability change of an egg when fertilised differs according to 
the species of sperm used — in other words, the degree of 
permeability change should be a function of the sperm.^ 
Jn conclusion, I wish to express my sincere thanks to Mr. 
Doncaster for much valuable advice during the progress of 
this work, and to Dr. Shearer for his valuable help in the 
preparation of this paper for publication. I also wish to 
thank the officials of the Plymouth laboratory for their un- 
failing assistance in obtaining material. 
VIII. Bibliogkaphy. 
1. Baltzer, F. — " Ueber die Beziehung zwischen deni Chrouiatiii und 
der Entwicklung nnd Vererbimgsrichtung liei Echinodermen- 
bastardeii. " ‘Arcli. fiir Zellforsclmiig.’ Bd. v. Heft 4, p. 497. 
191(1. 
2. Doncaster, L., and Gray, J. — " Cytological Observations on Cross- 
fertilised Echinoderin Eggs," • Proc. Camb. Phil. Soc.,’ xvi,pt. v, 
p. 41.5, 1911. 
2 a. " Cytological Observations on the Early Stages of 
Segmentation of Echinus Hjdirids." ‘Quart. Jonrn. Micr. 
Sci.,’ vol. -58, p. 483, 1912. 
3. Harvey, E. N. — ‘‘ Studies on the Permeability of Cells," ‘ Jonrn. 
Exp. Zool.,’ vol. X, No. 4, p. .507, 1911. 
4. Permeability of Living Cells to Alkalies," ‘ Year-book X. 
Carnegie Instit. Wash.,' p. 128. 
5. Hertwig, G. — “ Das Schicksal des mit Radium bestrahlten Sperina- 
chromatins im Seeigelei," ‘ Arch. f. Mikr. Anat.,’ Ixxix, abt. ii, 
p. 201. 1912. 
' As in some cases of hybridisation there is no doubt whatever that 
it is the male chromatin that becomes abnormal (e.g. Kupelwieser’s 
experiments), it is obvioiTS that changes of permeability of the cyto- 
j)lasm, as can be induced by the sperm, cannot be a sxifficient explanation 
of all the abnormalities observed in cross-fertilised eggs. 
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