SCIENCE-GOSS/J'. 



*45 



WATER -PL A NTS AND THE IK WAYS, 

 By II. B. Guppy, M J'- 



THEIR DISPERSAL AND ITS OBSERVATION. 



^"THOUGH it seems generally agreed that water- 

 fowl have taken an active part in stocking 

 oceanic islands with their aquatic plants, I do not 

 gather from the writings of English botanists that 

 they view with much favour the probability of the 

 birds transporting the seeds in their stomachs 

 across an ocean, in a condition fit for germination. 

 Darwin's researches and experiments are well 

 known in connection with this subject ; but, 

 sanguine as he was, he felt impelled to regard a 

 period of twenty-four hours as the limit of time, 

 and 500 miles as the limit of distance, that could 

 reasonably be permitted to the agency of birds in 

 stocking an island in this manner. De Candolle, 

 in his turn, looked to the ducks, the geese, and the 

 sea-birds to aid him in his difficulties of plant 

 distribution, but the facts failed him. Edward 

 Forbes was amongst the first to perceive the 

 necessity of the migrant water-fowl as plant- 

 dispersers, but I do not find that he gathered 

 many data. 



Nevertheless, I venture to think that some of 

 the readers of this journal might combine to aid 

 science in this matter, whether in this country or 

 abroad. A single observer could examine without 

 much difficulty, between September and March, 

 some twelve or fifteen specimens of a water-bird 

 common in his neighbourhood, such as the coot, 

 water-hen, wild duck, teal, widgeon, or any of the 

 waders. If resident on the coast his successes, 

 though less common, will be none the less 

 interesting ; and if on board ship in mid-ocean, he 

 will find in the albatrosses, petrels and Cape- 

 pigeons, the frigate-birds and the boobies, an 

 interesting field of inquiry. The writer once found 

 a small seed in the gizzard of a Cape-pigeon 

 in the South Atlantic ("Nature," xxvi., 12); 

 Sir \V. Milner found some curious nuts in the crops 

 of young petrels at St. Kilda (" Life and Letters of 

 Gharles Darwin," ii , 147, 148), and according to 

 Sir Ralph P. Gallwey, Brent geese feed extensively 

 on Zoster a maritima ("Shooting: Moor and Marsh," 

 Badminton Library, pp. 158, 161, 165). 



Anyone inclined to investigate this subject in 

 our own country would obtain sufficient materials 



for his purpose in what falls to the usual lot of the 

 sportsman, the keeper, and those engaged with 

 " decoys." In this manner, in the course of a few 

 years, a typical collection might be got together, 

 which would add greatly to our knowledge of 

 plant-dispersal, and could be ultimately offered to 

 some botanical museum. The contents of a bird's 

 stomach (crop, proventriculus and gizzard) can be 

 readily washed under a tap in an ordinary gravy - 

 strainer, and any small seeds that pass through 

 with the finer material can be easily separated by 

 decantation. For reasons to be given below, but 

 few seeds occur as a rule in the intestines, and 

 their examination often proves unproductive. It 

 will be better to mix the seeds with the food of a 

 bird and wash its droppings, noting carefully the 

 time that elapses between the first meal and the 

 appearance of the seeds in the ejecta, and the 

 length of time that the seeds continue to be dis- 

 charged after the last meal containing seeds has 

 been taken. Some fifteen or twenty of the seeds 

 found in a bird should, in the case of each kind of 

 plant, be tested for germination. They should be 

 placed at once in a saucer of water and kept 

 uncovered in a room, in a corner away from 

 direct sunlight. Some months may elapse before 

 germination begins if the observation is made in 

 the winter, but germination may commence even 

 in a few days. The seeds, when well advanced in 

 germination, should be placed in glycerine. In 

 birds which have been trapped the stomach often 

 contains also a quantity of grain, mixed sometimes 

 with such seeds as Polygonum, etc. For this reason 

 birds that have been shot will be more easily 

 examined. 



If my own experience is at all typical, there 

 ought to be but few failures in this field of inquiry. 

 Out of thirteen wild ducks obtained in the London 

 market during two winters, between September 

 and February, and stated to have been sent from 

 Norfolk and Holland, eleven contained in their 

 stomach and intestines seeds belonging to at least 

 ten different kinds of plants, and making a total of 

 828 seeds, which gives an average of sixty-three for 

 each of the birds examined. On comparing them 



