■270 REPORT— 1886. 



previous one, and a large series of microscopic preparations (chiefly sections 

 with the Caldwell and rocking microtomes) has been made chiefly by 

 Mr. E. E. Prince, embracing the entire development of the food-fishes 

 from the early ovnm to a late larval stage. The study of these prepara- 

 tions is now being proceeded with ; but in traversing a field so extensive 

 as the embryology of these important Teleosteans a great expenditure of 

 time and labour is required. It is hoped, however, that the results wiU 

 be completed during the winter.' 



Since the beginning of June Dr. Scharff" has been occupied with 

 the investigation of the iutra-ovarian egg of a number of Teleosteans. 

 Among the ovaries examined were those of Trigla gumardv^, Gadus 

 virens and G. luscus, Gadus inerlaiigus, AnarrMchas lupus, Conger vulgaris, 

 Blennius pholis, Lophius piscatorius, and Sabno salar. The researches were 

 made on fresh ovaries and on spirit-specimens. Most of those reserved 

 for section-cutting were previously treated either with picrosulphuric or 

 weak chromic acid. Special attention was paid to the structural changes 

 in the growing nucleus. The origin of the follicular layer surrounding 

 the egg, as well as the origin and development of the yolk, will be dealt 

 with in a paper to be published shortly. 



Considerable advancement has been made iu the study of the develop- 

 ment of the common mussel by Mr. John Wilson. Some of the very early 

 larvae are described in the Report of last year, along with an account of 

 the artificial methods employed. This year embryos were developed 

 for forty days in vessels suitable for microscopic manipulation. Normal 

 growth continued during the first fourteen days. At the end of this 

 period the largest embryos had shell-valves '128 mm. in length. They are 

 transparent and almost semicircular, the dorsal (hinge-) line being nearly 

 straight. The powerful velum could be wholly withdrawn within the 

 valves. The alimentary system was conspicuously developed. In the 

 beginning of June great numbers of young mussels were found swimming 

 actively on the very sui'face of the sea close to the shore, and measuring 

 •134 mm. They difi'ered from the most advanced of those artificially 

 reared only in their beiog more robust, the stage reached being the same 

 in both. At various periods somewhat later in the season many older, 

 though still microscopic, mussels were captured with the tow-net in St. 

 Andrews Bay from the shore seaward for four miles. Besides the careful 

 study of their development, Mr. Wilson has also been engaged with the 

 histology of the mussel (especially that of the generative organs) at various 

 stages, up to the adult condition. 



The Committee beg to recommend a renewal of the grant (lOOZ.) for 

 the ensuing year. 



' Vide for other observations the Annals of Natural History for April, May, June, 

 and August 1886 ; Nature, June 188G, &c. 



