632 MR, H. G. NEWTH ON THE 



CuGumaria planci (7), published without figures, and purporting 

 to be only the preliminary to a fully-illustrated memoir, has 

 generally been accepted as correct; but in the absence of his 

 completed work, which was never published, and in view of the 

 interest of some of his results, it was desirable that a fresh study 

 should be made. The suggestion that I should undertake this 

 research and the opportunity to conduct it I owe entirely to 

 Professor MacBride, whose encouragement and assistance I gi^ate- 

 fully acknowledge. 



My work on the embryology of Cucumaria had been in progress 

 for nearly three years, and was still in many respects incomplete, 

 when I learnt that Mr. H. Ohshima, Rigakushi, of Tokyo Imperial 

 University, was engaged upon similar researches. In these 

 circumstances the present short statement was prepared. No 

 attempt will be made in what follows to give, even in outline, a 

 picture of the whole period covered by my preparations ; it must 

 suffice to draw attention to those of my results which, on points 

 of importance, either confirm or cast doubt upon the conclusions 

 of Ludwig and others. 



Material and Method. 



My material consisted at first of a series of stages in the 

 development of Cucumaria saxicola, supplied by the Marine 

 Biological Association to Prof. MacBride, who handed them to 

 me for examination. I have since been able to add to this 

 certain stages in the development of the nearlj- allied C. normani, 

 adults of which species were sent to me in London. These 

 animals spawned in my tanks, as I shall describe, and gave me 

 the opportunity of observing the living larvae and of bridging- 

 certain gaps in the original series. I may say at once that 

 nothing can be seen, in the living young, of the internal changes 

 that are occurring, and that both stocks of material were fixed 

 in ignorance of the great rapidity with which the early develop- 

 ment takes place *, 



In view of the discrepancy between the statements made below 

 and those of Ludwig, it should be noted that the fixative used 

 by him was 50 per cent, alcohol followed by 70 per cent, alcohol. 

 Of my own methods of preservation and sectioning I cannot 

 treat in this place further than to say that the only reliable 

 fixatives Avere found to be the picro-formol-acetic mixture of 

 Bouin and Flemming's strong fluid (acting for not more than 

 two hours), and that the method of double-embedding in celloidin 

 and wax was always used. Special difficulties in orientation 

 necessitated a modification of the latter method, and this I hope 

 to describe at some length in my full account. Sections were 

 generally cut 6 /u thick, and were stained with an alcoholic 



* Since the above was written a consignment of C. saxicola, from Plymoutli, 

 has provided uie with abundant material for a complete afceount of the development 

 of that species. The description here given of spawning, seguieutation, etc., in 

 C. normani applies with equal truth to C saxicola. 



