S'2 TRAXSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



blood of teleosts from the aquarium tanks had a lower 

 osmotic pressure than blood from freshly-caught (living) 

 fish from the sea. There was a possibility that this 

 difference might be due, in an indirect manner, to 

 differences in hydrostatic pressure. In order to 

 determine the factor bringing about the abnormal con- 

 stitution of the aquarium fish, a number of living plaice 

 were taken out to sea in the ' Runa,' and half were 

 lowered in a perforated box to the bottom in about 20 

 fathoms of water, whilst the remainder were kept at the 

 surface in a floating box. Full details of the methods 

 employed will appear in the paper (to be published in 

 the ' Internationale Revue d. Hydrobiologie 'j. The 

 osmotic pressure of the blood from both the batches of 

 fish was found to be identical. Evidently, therefore, 

 dift'erences in hydrostatic pressure are not responsible 

 for the differences previously observed in the blood, and 

 other aquarium conditions must be examined in order to 

 find the cause of the abnormalities. 



"Ill connection with my work on the Whelk 

 {Bnccinnm undatuvi), which was continued at Port Erin 

 both in the Easter vacation and during September, some 

 details may be of interest. It has already been shown 

 that one can almost always be certain of finding stages 

 of an interesting Coccidian parasite in the renal organ, 

 and that for class work this may be regarded as a good 

 example of a Sporozoon easily obiiiined. Another 

 parasite occurs in the stomach and icctum — namely, an 

 endo-parasitic Turbellarian (ii rdf'dln hiiccinicola). As 

 almost every whelk appears to be infected and contains 

 on an average about a (h)zen sj)ecimens, this may also 

 be taken as a convenient type for laboratory teaching- 

 purposes. It is ])aiticulaily valuable, since endo- 

 parasitic 'I ui bclhiiia arc by no means common. The 



