222 TEANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



of my series of sections, consisting of (1) a complete series 

 of transverse sections of the entire animal cut from end to 

 end, and arranged serially (containing some 600 or 700 

 sections), (2) a seiies of longitudinally cut sections, (3) 

 various sections of cerata isolated from the body, cut in 

 every direction. I minutely compared the figures published 

 in 1889, with the particular sections from which they were 

 drawn, and made fresh dissections of the animal. The 

 result of my work in this direction was to verify in every 

 particular the conclusions come to in our former paper 

 with regard to the cerata. I then set myself to consider 

 in what further directions I could proceed in order to 

 obtain additional evidence, and it occurred to me that a 

 series of sections cut horizontally, in a plane as nearly 

 parallel as possible with the creeping surface, would be of 

 great service. I could then pass from section to section, 

 tracing the liver from below upwards to its most dorsal 

 terminations, finally cutting transversely through the 

 bases of the cerata themselves ; and by this means 

 determine exactly the relations of the liver to the bases of 

 the cerata. I obtained some living Dendronotus, from 

 Hilbre Island, and as the histological methods employed 

 were not described previously I will here describe them. 

 The Dendronotus is allowed to expand in a little 

 sea-water, and then deluged with sulpho-picric acid 

 (Kleinenberg's formula), which by a rotatory movement 

 of the hand is made to whirl round in the vessel. This 

 treatment has the effect of fixing nudibranchs before they 

 can retract. Even with the more delicate species of 

 Eolidse, which, with almost all other methods, break 

 away the cerata from the body, this method is usually 

 successful. The specimens are allowed to stand in this 

 fluid, changed once or twice, for two or three hours 

 according to size. They are then transferred to gradually 



