ON THE LABORATORY OF THE MARINE BIOLOGICAL ASSOCIATION. 345 



Investigations made at the Laboratory of the Marine Biological Associa- 

 tion at Plymouth. — Report of the Committee, consisting of Professor 

 E. Ray Lankester (Chairman), Professor M. Foster, Professor 

 S. H. Vines, and Mr. G. C. Bourne (Secretary). 



On the Development of Alrymiium . Bij Dr. S. J. Hickson. 



On, the Later Stages in the Developvient of Becapod Crustacea. By Edgar J. Allen. 



The Committee were appointed for the purpose of enabling Dr. S. J. 

 Hickson to investigate the development of Alcyonium at the Laboratory 

 of the Marine Biological Association, Plymouth. 



The Committee have received the following report from Dr. Hickson, and 

 a supplementary report from Mr. Edgar J. Allen, who occupied the table 

 during June and July 1893 : — 



On the Development of Alcyonuim. By Dr. S. J. Hickson, M.A. 



On my arrival at Plymouth early in the month of December last I 

 experienced a great difficulty in obtaining a sufficient quantity of material, 

 in consequence of the severe storms then raging. The few specimens of 

 Alcyonium I obtained contained large quantities of ripe ova or sacs con- 

 taining ripe spermatozoa. They spawned freely in the tanks of the 

 aquarium, but I was not successful in fertilising the ova artificially, as the 

 water of the tanks affected injuriously the spermatozoa. I succeeded, 

 however, in obtaining a few young embryos by keeping the specimens iu 

 fresh sea-water in buckets. Soon after Christmas the sea became calmer 

 and I obtained plenty of colonies, but they were nearly all spent and 

 useless for my investigations. 



The results I have obtained confirm those of Kowalewsky. I can find 

 no trace of any karyokinetic division of the first segmentation nucleus, 

 although these figures can be easily demonstrated in the later stages. 

 While I was waiting for sufficient material to study the embryology of 

 Alcyonium, I devoted a considerable amount of time to a study of the 

 minute anatomy and physiology of the genus. A full account of these 

 investigations will appear in a paper now nearly ready for publication. 



Researches on the Later Stages in the Develoj)ment of Decapod Crustacea. 

 By Edgar J. Allen, B.Sc. London. 



My attention during the months, June and July 1893, when I occu- 

 pied the Association table, was devoted chiefly to the study of the 

 nervous system. After repeated trials on a number of decapod embryos 

 and larvas, a satisfactory subject for research was found in the embryonic 

 lobster, many of the nerve elements of which stain excellently in dilute 

 solutions of methylene blue. My observations, after being coiitinued and 

 extended, were published in a preliminary paper read before the Royal 

 Society in April 1894, whilst a fully illustrated account will shortly 

 appear in the ' Quarterly Journal of Microscopical Science.' 



The following nerve-elements are amongst the most important of 

 those which I was able to demonstrate during the time which I occupied 

 the Association table : — 



(1) Elements starting from a cell in one ganglion of the thorax and 

 giving off a fibre, which, after sending numerous arborescent branches to 



