560 SECTIONAL TRANSACTIONS.— D, 



traversed. The instrument is described and the results — records totalling some 

 2,400 miles — discussed ; considerable patchiness is shown even in oceanic waters. 



More detailed researches into patchiness were made by means of a series of con- 

 secutive tow-net hauls which revealed remarkable patches of Euphausians and Hyperiid 

 Amphipods. The causes of uneven distribution are discussed. 



Mr. R. Elmhirst. — On the Work of the Millport Laboratory. 



A short account of the history and equipment of the station, with mention of the 

 natural advantages due to its geographical position. The purity of the water supply 

 in the aquaria is exceptional, giving special facilities to the experimental biologist. 

 The scope of past work indicated and an account of recent investigations, chief! v 

 planktonic, will be given. 



Miss P. M. Jenkin. — A Preliminary Account of an Investigation of the 

 Plankton of Loch Awe in relation to the Physical and Chemical 

 Conditions of the Water. 



Friday, September 7. 



Dr. 0. W. TiEGS. — On Neurofibril Continuity. 



While it seems quite clear that ultimately there must be discontinuity in the 

 integrating region of a reflex arc — in the sense that an impulse must pass from a 

 region where conduction in both directions can occur, to one where forward conduction 

 alone takes place — it does not follow that such discontinuity is in the form of a visible 

 gap between the terminal branches of a neurone and the next cell of the chain. The 

 author finds that in spinal cord cells, Mauthner cells, and cells of the ventral acoustic 

 nucleus of fish, no visible gap in the neurofibril chain occurs, and that blind endings 

 of neurones are due to incomplete staining. 



Dr. E. Stedman. — The Reversible Combination of Hcemocyanin with 

 Oxygen. 



Hsemocyanin is a protein containing copper, present in the blood of certain 

 invertebrates. It combines reversibly with oxygen, and is practically colourless in 

 the reduced condition and blue in the oxidised. A study under carefully controlled 

 conditions of the oxygen dissociation curves of the hsemocyanins from a number of 

 species (Cancer pagurus, Homarus vulgaris, Limulus polyphemus. Helix pomatia) has 

 revealed such marked differences in their behaviour towards oxygen as to leave no 

 doubt as to their specificity. The affinity for oxygen of the hamocyanins from 

 Cancer and Homarus varies considerably with the hydrogen-ion concentration, and 

 is found to be related to the viscosity of the solution, the afiinity curve being antibatic 

 to the viscosity curve. In the case of the pigment from Cancer, the ^H (7-3) at which 

 the viscosity of its solutions is at a maximum practically coincides with the p'H. at 

 minimal affinity, from which it would appear that the affinity for oxygen of the 

 haemocyanin anion is smaller than that of the undissociated pigment. On the other 

 hand, the power of the hsemocyanin from Helix to combine with oxygen is, in salt-free 

 solutions, uninfluenced by jjH. The curve is, moreover, of the hyperboUc type, which 

 would be expected if the pigment were molecularly dispersed in solution and combined 

 with oxygen according to the equation Hcy-fO.^ _ * ffr-iiVt. 



Prof. A. D. Peacock. — Parthenogenetic Male and Female Production by 

 two kinds of Females in one and the same Species of Saivfly. 



From larvae collected in Nature both sexes of the saw-fly Thrinax macula, Kl., 

 have been reared, the sex-ratio being 100 males : 560 females. The males emerged 

 and died before the advent of the females, so that sexual reproduction could not be 

 studied. However, from thirty-four experiments with single virgin females, both 

 sexes have still been obtained by parthenogenesis, the sex-ratio being 100 males : 

 290 females. Of these 34 parthenogenetic females 3 gave non-viable larvaR, 27 gave 

 females only (thelytoky) and 4 gave (to date) respectively 22 males and 1 female. 



