340 



explanatory figures would make the observations easier to follow, 

 and he had asked Mr. Merlin to send them, 



Mr. Morland said Mr. Merlin had called attention to the 

 difficulty in seeing some of these valves properly ; he thought this 

 was due to the method of mounting. If they were fixed first with 

 gum this would prevent the medium from penetrating; and if, 

 instead of mounting them upon the cover they were mounted on 

 the slip, by introducing some small discs of definite thickness, the 

 cover could be put down at a known distance from the slip and 

 quite close enough to work with an immersion objective. If they 

 tried to do this empirically they might either put the cover too 

 close and thereby smash the diatom, or they might have it too 

 far to be able to see it in focus. 



Mr. Karop said that the excellent device mentioned by Mr. 

 Morland was described in a back number of the Journal, vol. 5, 

 p. 4, on " Mounting Selected Diatoms." It was a most useful 

 suggestion. 



The thanks of the Club were voted to Mr. Merlin for his 

 interesting notes. 



Mr. Karop made some remarks on the extreme degree of 

 specialisation that is now evident in work on Cytology, and 

 referred especially to a classification of the subject suggested by 

 the late Dr. A. Graf (see Note, p. 315). 



Mr. Karop further called attention to a remarkable paper which 

 seemed to upset all the accepted ideas as to the process of fertihsa- 

 tion. In the "Comptes Eendus," cxxix. 1899, Professor Yv^es 

 Delage, in recording his experiments on fertilisation, states that 

 a non-nucleated fragment of the ovum of Echimos, Dentalium, or 

 Lanice may be effectively fertilised, and give rise to a Pluteus, 

 a Veliger, or a Trochophore respectively. Three larvae may be 

 reared from one ovum of a sea-urchin, and a normal blastula 

 was obtained from a ^^th. fragment. There is a cytoplasmic 

 maturation distinct from the nuclear maturation. Non-nucleated 

 fragments seem to be fertilised more readily than normal ova. 

 It seems as if the essential fact of fertilisation were not the 

 fusion of nuclei, but the union of a sperm-nucleus with a mass 

 of ovum cytoplasm. 



The President said they were very much obliged to their 

 Hon. Secretary for his remarks in bringing these subjects before 

 them, he was inclined to agree with him as to the feelings of 



