The President's Address. By Dr. G. T. Hudson. 173 



lily-tank at Eaton Hall, but till quite lately in no other country. 

 Now I have just received a letter from Mr. Gunson Thorpe, telling 

 me that he has found it swarming in a pool on a rocky headland in 

 Queensland. 



You have no doubt, long ere this, anticipated the solution of the 

 puzzle ; and see clearly enough that living creatures, to whom a yard 

 of sea-water is as impassable a barrier as a thousand miles of ocean, 

 could only have reached or left Australia, New Zealand, Jamaica, 

 Ceylon, &c., in the egg ; not the soft, delicately shelled, quickly 

 hatching, summer egg, but the ephippial egg, which is protected by 

 a much harder and thicker covering, which is constructed so as to 

 bear without injury a long absence from the water, and which 

 hatches, so far as is known, some months after it has been laid. 



But this explanation still requires to be explained. The case of 

 the free-swimming Eotifera is simple enough. They are most of 

 them to be found, at some time or another, in small shallow pools ; and 

 their eggs either fall to the bottom of the water, or are attached to 

 the small confervoid growth on the stones in it. Such pools fre- 

 quently dry up, leaving the ephippial eggs to wait for the rainy warm 

 weather of next year. Then comes boisterous weather, and the dusty 

 surface of the exposed bottom of the pool is swept by a wind which 

 raises the dust high into the air, ephippial eggs and all. For these 

 latter are minute things, few exceeding 1/300 in. in length, and many 

 even half that size. Once raised in the air, I see no reason why they 

 should not be driven by aerial currents, unharmed, half round the 

 globe, falling occasionally in places where water, temperature, and 

 food are alike suitable. The dust of the eruption at Krakatoa, which 

 gave us such wonderful sunsets and green moons in 1883, travelled 

 &om the Sunda Isles to England in three months, and so the ephip- 

 pial eggs of Asplancima Ehbeshornii and other Eotifera may have 

 traversed the distance from England to Australia, and yet have been 

 capable of hatching at the end of the journey. 



It may perhaps seem a fanciful notion to account for the stocking 

 of the ponds at Sydney by eggs carried thousands of miles in the air, 

 but several well-known facts warrant the hypothesis. The tops of our 

 houses, the heights of the Alps, the slopes of the Siberian mountain- 

 ranges, are the haunts of the Philodines ; which, being an exception- 

 ally hardy race, have accommodated themselves to living in damp 

 mosses at the edge of a glacier ; or in a gutter, which now holds a 

 mere handful of stagnant water, now is a racing current, and now a 

 dusty leaden basin, glowing under a blazing sun. No doubt eggs of 

 all sorts of species fall on the same spots, but only to perish under 

 trials that none but a Philodine could survive. 



How various are the species, whose eggs are thus wafted up by the 

 air, has been well shown by Mr. J. E. Lord ; who has given a list of 

 no fewer than forty-five species (contained in twenty-nine genera) 

 that he found in the course of twelve months in the same garden- 

 pond. It was, however, admirably situated for catching whatever 



