ON THE ZOOLOGICAL STATION AT NAPLES. 183 



II. Beport on the Occupation of the Tahle hy Mr. Francis G. Penrose. 



I asked for permission to use the British Association's table at 

 the Zoological Station at Naples, so that, as I was obliged to leave England 

 by medical advice at the beginning of this year, for three months, 

 I might, if possible, employ a portion of my time in endeavouring to get 

 some° practical idea of general marine zoological work, especially with 

 reference to the numerous invertebrate larval forms: their mode of 

 capture, appearance, and the means in use at the Station of preserving 

 them and showing their structure. The only point which I proposed to 

 myself for special investigation was the vascular system of LameUibranchs, 

 which had been suggested to me by Professor Lankester in connection 

 with Solen legumen. » • t 



Many eminent naturalists— as Lacaze-Duthiers, Agassiz, Langer-- 

 have studied the subject, and have demonstrated many points, both in 

 the o-eneral course of the circulation and the channels through which the 

 bloocl passes. In doing so they have almost invariably had recourse to 

 artificial injection, which, though it has shown a great deal of much 

 importance, has not proved entirely successful, probably because the 

 arterial and venous portions of the circulatory system appear not to be 

 connected by definitely-walled capillary passages, but that the blood finds 

 its way, after leaving the arteries, amongst and between the various 

 tissues and organs of the body, and is only re-collected into true 

 sanguiniferous tubes near the great vena cava. 



So that further investigation was still necessary, to decide such 

 questions as to whether any blood passes into the ca.vity of the pericar- 

 dium ; and, if so, what becomes of it ? Whether the apertures which con- 

 nect the vascular system with the exterior are only for the inception of 

 external fluid ; or whether, under any circumstances, liquid contained, m 

 the vessels is able to pass outward through them ? In fact, whether the 

 liquid which is so copiously thrown out by a Lamellibranch, on con- 

 traction, consists of blood, or of any portion of the blood-fluid ? Solen 

 legume7i seemed to be particularly favourable for the study of these 

 questions, as the blood of this animal, besides possessing ordinary 

 colourless corpuscles, is particularly rich in bright red corpuscles, 

 discovered by Professor Lankester, and shown by him to contain 

 hsemoglobin, which forms a perfectly natural injection; and, as will be 

 seen from what has been said above, this is a point of very great 

 importance. Unfortunately, notwithstanding the exertions made to 

 obtain for me as many individuals of this species as possible, but very 

 few were forthcoming, and those were nearly all full-grown, which were 

 not very suitable, owing to the want of transparency and to the practical 

 diCBculties of manipulation,— the slightest injury rendering the individual 

 useless for the research. But, from what I saw in them, I venture to 

 think that, had it been possible to obtain younger specimens, they would 

 have enabled me to settle those questions I was hoping to answer. As a 

 definite result, I consider that (at any rate, in the only individual that 

 allowed me a favourable examination) there were not any red corpuscles 

 in the cavity of the pericardium, excepting, of course, those contained 

 within the heart. In conclusion, I have to thank the staff at the Station 

 for the constant facilities and assistance they afforded me. 



