262 



NA rURE 



\Jan. 17, 1884 



know the two words when printed on cards, YES or NO, and 

 after a few weeks' teaching he never mistook them. I have no 

 time now for much teaching ; if I hart, I am sure it could be 

 done with tlie dog I now have. The intelligence of cats is 

 greatly underrated. My wife's favourite cat follows her every- 

 where, and comes when called wherever she may be. Cats, too, 

 are very grateful for kindness. When I went into the Malakhoff 

 I found a cat on whose paw a bayonet had fallen and pinned it 

 to the ground. I released it and took it home, and it always 

 followed me all over the camp till the end of the war. And this 

 cat did as follows. I took her to a doctor of the nearest regi- 

 ment for two mornings to have her foot dressed. The third 

 morning t was away on duty before daylight, and the cat w ent 

 herself to the doctor's tent, scratched the canvas to be let in, and 

 then held up her paw to be doctored. The intelligence that can 

 be developed in almost any animal depends in most cases on our 

 treatment of it. H. Stuart Wortley 



South Kensington Museum, S.W., January 14 



Circling to the Left in a Mist 



One generally reads that persons walking without landmarks 

 perform a large circle and cut their old tracks again. This 

 circling, as far as my present knowledge goes, is to the left. 



My present theory is that in most persons the right leg is the 

 stronger and the more forward to step over any obstacles, and 

 hence that it slightly outwalks the left ; this theory involving as 

 further consequences that those in whom the left leg is the 

 stronger would circle to the right, while those ^^h^se legs are of 

 equal strength would either keep straight on or would wander 

 either way indifferently. I imagine this " outwalking " of one 

 leg by the other to be similar to the manner in which a body of 

 troops wheels to one side or the other. 



In the following I use the expression "right-legged." By this 

 I mean that the right leg is that chosen to kick with, jump 

 from, <S:c. 



My negative evidence is as follows : — 



1. I myself am right-legged, and in a mist I always circle to 

 the left. I have only come across cases similar to my own in 

 these respects. On the other hand, my left arm has been trained 

 (by always rowing on the bow-side) to be stronger than my right 

 for rowing purposes ; and in sculling I always circle to my right 

 side. 



2. Those savages of whom I have read that they could keep 

 a straight course without any landmark were also represented as 

 using both arms (and legs ?) impartially. 



I have given the above evidence chiefly to show how weak it 

 is, in the hope that some of your readers will try to collect data 

 of the following nature from any of their acquaintance \\ ho have 

 had experience in the matter : — 



(a) To which side, if any, do they circle ? 



(b) Are they right- or left-armed, right- or left-legged ? or are 

 the two sides equally strong? 



It might also be interesting to learn from boating friends if 

 they have observed any connection between the side on which 

 they have been accustomed to row and the side to which they 

 circle in sculling ; such connection as that indicated above. 



Finally, I may suggest that more mi;^ht be known on the 

 question of the heredity of right- or left-sidedness ; and as to 

 whether persons are often right-armed but left-legged, &c. But 

 it must be remembered that tendencies of this nature are often 

 " educated out " in childhood. W. Larden 



Cheltenham College 



THE PORPITID.E AND VELELLID^ 

 pROFESSOR ALEXANDER AGASSIZ has quite 

 -'■ recently (July) published an important contribution 

 to our knowledge of the morphology and embryology of 

 these families of marine Hydrozoa. This appears as one 

 of the quarto memoirs of the Museum of Comparative 

 Zoology at Harvard College, and is illustrated with twelve 

 plates. While at the Tortugas, during March and April, 

 1 88 1, examining the structure of the coral reefs, Prof. A. 

 Agassiz took advantage of every possible opportunity of 

 exploring the surface fauna of the Gulf Stream, and when 

 not otherwise occupied he devoted his time to comjilcting 

 the notes and drawings «hich he accumulated regarding 



Porpita and \'elella under less favourable circumstances 

 at other points of Florida, at Newport, and on board the 

 Blii/ce. These notes are now published as forming the 

 principal points in the natural history of a small and 

 litnited group of oceanic hydroids, interesting from their 

 affinities on the one hand to the Tubularians, with which 

 V'ogt, KoUiker, and .■^gassi^ were inclined to associate 

 them, End on the othtr hand with the Siphonophora; 

 proper, with which they have, however, but little in 

 common. Mr. C. O. Whitman was sent this spring to 

 Key West to complete this memoir, and especially to in- 

 vestigate anew the whole subject of the structure and 

 functions of the so-called yellow cells ; but although he 

 spent six weeks at Key West, he was unable to accom- 

 plish the object of his trip, as not a single \'elella 1 

 appeared at Key West during the whole of his visit. J 

 Under these circumstances Prof. A. Agassiz thought it I 

 advisable to at once publish his drawings and notes, com- J 

 pleting the descriptive part when the necessary prepara- I 

 tions can be finished. The Florida species of Velella (F. \ 

 miitica, Bosc) is inuch larger than the Mediterranean 

 form {V. spiralis); specimens measuring nearly four 

 inches in length are not uncommon. On plate i is 

 figured in profile and from above and below a huge \'elella 

 nearly five inches in length, and in all the glories of its 

 metallic colouring. Thousands of this species are brought 

 by favourable winds and tides into Key West Harbour ; 

 they are usually seen in large schools, and although 

 capable of considerable independent movement by means 

 of their tentacles in a smooth sea, yet are they practically 

 at the mercies of the winds and currents. Even mode- 

 rate waves destroy them in vast numbers. When kept 

 in confinement they soon die, and are rapidly decom- 

 posed. The dead floats are thrown ashore in enormous 

 numbers. The large central polypite of the system is the 

 main feeding mouth, but the smaller lateral polypites feed 

 also to a limited extent. All these are connected at their 

 base with the general vascular system, through which as in 

 the polypites the fluids are rapidly propelled by the action 

 of cilise lining the inner walls. At the base of the polypite 

 there are, according to its size, from five to eight clusters 

 of Medusse buds : the small ones already contain the 

 peculiar yellow cells so characteristic of the free Medusa;. 

 The young Medusa; have a vtry striking resemblance to 

 such Tubularian Medusa as Esuphysa and Ectopleura. 

 It has like them a row of lasso cells extending from the 

 base of the tentacles to the abactinal pole. The yellow 

 cells are arranged in clusters along the sides of the four 

 broad chymiferous tubes, as well as on the surface of the 

 short, rounded, conical, rudimentary proboscis. The 

 young Medusa; move with considerable activity by sudden 

 jerks. The air-tubes branch much less frequently than is i 

 the case in the Mediterranean species. AH the Velellse 1 

 floats examined were left-handed. | 



The Florida species of Porpita (/". Unneana, Less.) is 

 nearly related to but is larger than P. lueditcrranea. It 

 is capable of a considerable control over its movements, and 

 is not stranded at all in the same numbers as is A'elella. 

 If upset by wind or waves it can, by the great size 

 and power of its numerous long marginal tentacles 

 force itself back again into its normal position. It does 

 this by bringing its tentacles together over the disk 

 and throwing up the free edge of the mantle slowly 

 in a given direction, then expanding the tentacles of one 

 side far over in the opposite direction beyond the central ^ 



part of the disk, it readily changes the centre of gravity, 

 and so tilts the overturned disk back again. Round the base 

 of a large central polypite are five to six rows of small, 

 stout, flesh-coloured, feeding and reproductive polyps ; 

 these have a slightly rectangular head capable of con- 

 siderable expansion, with four clusters of lasso cells. -\t 

 their base are to be found Medusa; buds in all stages of 

 development. When the clusters of these are well deve- 

 loped they completely fill the space between the small 



