3o6 DISCOVERY REPORTS 



The electricity supply at Arrecife used to be cut off at i a.m., after three warning flicks given a 

 quarter of an hour previously. So it was always a race against time at the end of a busy day to 

 transfer specimens to buckets and plastic bowls of fresh seawater; to get rid of stale water and mori- 

 bund specimens, which I always deflated with a pair of scissors to avoid re-collection; and to reach 

 one's bedroom and light a candle before the lights went out. 



NON-TECHNICAL DESCRIPTION OF THE PORTUGUESE MAN-OF-WAR 

 For the benefit of the reader who does not wish to examine minutely the structure of Physalia, I will 

 attempt to give in plain language a short account of its significant features with the least assumption 

 of previous knowledge. 



The conventional idea of a marine animal must be forgotten. Physalia is very simply organized, 

 without head, tail, limbs, skeleton, mouth, alimentary canal, anus, gills, blood-vessels, body-cavity, 

 kidneys, brain or one-way-traffic nerves. It is really an overgrown polyp-like* larva, belonging to the 

 Cnidaria, the group which includes jelly-fish, corals and sea-anemones. It floats on its side and, 

 without growing-up into a sexually mature animal itself, produces underneath as buds, innumerable 

 similar daughter polyps — these too are really in the larval phase — which bud again and produce 

 thousands of minute and not fully formed adults, having the essential structure of a jelly-fish or 

 medusa, and which are called gonophores.f Though not fully formed like the usual jelly-fish, the 

 gonophores represent the adult, sexual phase ; and in any one specimen are all either male or female. 

 The daughter polyps also bud off non-sexual simplified adults for propelling the broken-off branchlets 

 which bear the true sexual adults. 



So, in Physalia, we have two components to think of: 



(i) The original polyp, hatched from the egg, which becomes a sort of nurse carrying about the 

 innumerable buds to which it gives rise. An asexual larva itself, it not only buds off other larvae, but 

 adults as well, both asexual and sexual. The larva is a hollow sac with a mouth at one end and only 

 a single tentacle (PI. VII, fig. 2) ; it develops from a fertilized egg and becomes very much enlarged and 

 continues to float. The much enlarged original polyp itself extends from one end of the specimen to 

 the other. One end is free of buds and has near its tip a pore communicating with the enormous air- 

 sac, which as a small depression during the early development becomes pushed inside the float-end of 

 the polyp. At the other end, the mouth, stomach and tiny tentacle of the original polyp soon become 

 nearly hidden by all the daughter buds (PI. VIII). 



(2) We must consider these daughter buds: some of them take in and digest the food, some consist 

 chiefly of a long stinging tentacle, others, the palpons, appear to be protective and sensory, and 

 the remainder are the little imperfect sexual adults (the gonophores) and the asexual medusoids (the 

 swimming bells or nectophores). 



In no other cnidarian do we find such prolific budding as in Physalia (PI. IX). After the original 

 polyp has hatched from the egg and has assumed the horizontal position characteristic of the species, 

 and the aboral float has begun to enlarge, the first buds begin to appear on the under-surface in the 

 middle part of the polyp. Later buds arise in turn from the bases of the first buds which soon elongate, 

 so that subsequent series of buds are borne on stalks or peduncles. The first series of buds is arranged 

 in two major zones: an oral zone of at least five small peduncles separated by a gap, the basal internode, 

 from a larger main zone of six or seven peduncles. As series after series of buds appear, each laterally 



* A polyp has the shape of an elongated cylinder fastened at one end, with a mouth and one or more tentacles at the free 

 end. The name is derived from the French word 'poulpe' meaning octopus with its mobile tentacles. 

 ■f I find that Leuckart (185 1) had long ago come to the same conclusion. 



