TRANSACTIONS OF SECTION D. 693 



MONDAY, SEPTEMBER 14. 

 The following Papers were read : — 



1. On the Significance of Progamic Nihclear Divisions, 

 iiy Professor Marcus Hartog. 



2. Nuclear Changes in the Eqg of Alcyonium. 

 By M. D. Hill, M.A. 



3. The Function of Chromatin in Cell Division {Part I. Heterotype). 

 By Professor Marcus Hartog. 



4. Discussion on Fertilisation, in which the following took part : — 

 Professors Hickson, Farmer, Hartog, and Messrs. W. Bateson', 

 M. D. Hill, and J. W. Jenkinson. 



5. On the Tentacles of Suctoria. By Professor Marcus Hartog. ' 



6. Demonstration of Slides showing Conjugation in Dendrocometes, 

 By Professor S. J. Hicksox, F.B.S. 



7. The Effect of Solutions of Salt and other Substances on the Develo2)ment 

 of the Frog. By J. W. Jenkinson, M.A. 



0. Hertwig and others have shown that the course of development of frogs' 

 eggs grown in certain solutions of salt and other substances is abnormal. The 

 abnormalities consist in the formation of a large persistent yolk-plug, due to the 

 failure of the lips of the blastopore to grow over the yolk and in the incomplete 

 closure of the medullary folds. 



The following investigation was undertaken in the hope of determining whether 

 the effects observed are due entirely, as has been maintained, to the increase in 

 the osmotic pressure or to the change in the chemical composition of the medium 

 as well. 



The eggs were placed in a solution of -625 per cent, sodium chloride, and in 

 isotonic solutions of cane-sugar, grape-sugar, m-ea, potassium chloride, and lithium 

 chloride. 



During the first two days development was sensibly similar in all the eggs, 

 but slower than in the normal controls. Subsequently, however, while the mal- 

 formations which were produced were in all cases similar in kind they differed 

 greatly in degree. 



In urea the blastopore closed at a later period than usual, but in other respects 

 development was fairly normal. The tadpoles died. In cane-sugar and dextrose 

 the blastopore was late in closing, and the medullary groove remained open, in the 

 latter case widely open. In the chlorides of potassium and lithium the yolk re- 

 mained almost entirely uncovered, and the embryos died almost before the 

 formation of the medullary folds. In sodium chloride they lived longer ; the 



' Published in the Archivfur Protistenkunde, Bd. I. 1902, pp. 372-374. 



