ON THE MARINE BIOLOGICAL LABORATORY, PLYMOUTH. 585 



1894), and the stain as fixed by the ammonium molybdate solution (after 

 Bethe's recipe). The preparations were dehydrated and cleared by slow 

 diffusion into xylol or cedar-wood oil . At first I employed an injection 

 of a -1 per cent, solution of methylene-blue, but I soon found that better 

 results could be obtained by rapidly dissecting out the nervous system 

 and watching the progress of the stain under the microscope. The best 

 temperature for rapid staining of unaltered nerve-fibres is about 65'^ F., 

 while in passing the preparations through alcohol a low temperature is 

 advisable, otherwise the stain is liable to be washed out. 



Nereis, Polynoe, and Halosydna gave the best results. The elements 

 of the nerve-cord of Nereis diversicolor, though delicate, are rapidly 

 stained before the fibres have time to ' bead.' The number and arrange- 

 ment of the nerve-elements in this species are still occupying my attention. 

 Unfortunately only a couple of specimens of Halosydna gelatinosa were 

 obtained during my stay at Plymouth. The somewhat short nervous 

 system, the ease with which it can be exposed, and the stoutness of many 

 of the fibres, are great advantages in dealing with this species. 



With regard to the tubicolous Polychtets, my experience agrees with 

 that of other observers. The method that gives excellent results in 

 Nereis, at the same time and under the same conditions, fails to stain 

 diSerentially the elements of the cord in Arenicola or Cluetoptenis. Out 

 of a large number of preparations of Arenicola Grubii a few only show 

 the course of a small number of nerve-fibres. I hope, however, by 

 modifying the stain to obtain better results than heretofore. 



In conclusion, I wish to tender my sincere thanks to Mr. E. J. Allen, 

 the Director of the Plymouth Laboratory, for placing the resources of the 

 laboratory at my disposal, and especially for his kind assistance and 

 advice. 



Reiiort on Mr. J. H. "Wadsworth's collection of material for the Study 

 of the Embryology of Alcyonium. By Professor S. J. Hickson, F.R.S. 

 On arriving at the laboratory on December 31, Mr. "Wads worth found in 

 one tank (which I will call Tank I. in this report) sixteen healthy colonies 

 of Alcyonium, which had been placed there twenty-four hours previously 

 by Mr. Allen. The water in this tank contained a number of embryos in 

 diSerent stages of development up to the stage they reach in twenty-four 

 hours. These were all removed and preserved, some in corrosive subli- 

 mate and acetic acid, some in Hermann's fluid, and some in Mix. No. 3 

 (chloroform, acetic acid, and absolute alcohol). In another tank (Tank 

 II.) there were about sixty colonies, many of which were not in a 

 healthy condition. In the water of this tank there were numerous 

 embryos, some of which were clearly abnormal and unhealthy. Thirty- 

 six of the colonies from this tank were removed to fresh sea-water in 

 Tank III. 



During his stay at Plymouth Mr. Wadsworth collected at different 

 times the embryos that were found free in the water of these three tanks, 

 and preserved them in various reagents, noting, in each case, carefully 

 the time that had elapsed since the water was free from embryos. 



On January 3 a female colony was placed in a bell jar by itself, a 

 quantity of ripe sperm was added to the water, and Mr. Brown's agitator 

 employed for keeping the water in the bell jar in motion. Some of the 

 embryos shot out by this specimen were preserved ten liours afterwards 

 in the corrosive-acetic mixture, the remainder were isolated and pre- 



