SCIENCE AND INDUSTRY. 
compensate for the dispersal of the prickly pear seeds. There seems little evidenca 
as yet in New South Wales incriminating other birds that fly, but it is frequently 
stated, and on good grounds, that the emu is an efficient means of dispersal. Emu 
droppings frequently contain the seeds. . Their powerful build enables them to- 
overcome, to some extent, their handicap in not being able to fly, so that they 
may pass from paddock to paddock by getting through fences, ‘The part that 
the emu may play in the problem is, however, one that must be scientifically 
investigated with care and thoroughness before the bird can be condemned. In 
soine districts the aborigines are said to feed freely on prickly pear, State, 
ments have been made that prickly vear plants frequently grow up where these 
persons have defewecated behind trees. Care should be taken in sifting such 
evidence, and experiments planned to prove or disprove this possible minor factor 
in the spread. Wien prickly pear plants erow along watercourses, be they 
WILD COCHINEAL (Coccus confusus News cadi—on Nopalea ecchinetfera) Antigua, 
West Indies. 
low banks liable to flooding, er rocky gorges, the flood waters may dislodge 
segments of prickly pear, and distribute them lower down in their courses, ihe 
heavily inseminating possibly hitherto unafected areas. .Some of the exceed- 
ingly prickly species of Opuntia, fortunately of kinds at present lecally circum- 
scribed, have joints so easily detached and spines so arranged that the segments 
themselves might easily be transmitted over considerable distances by quadru- 
peds. Such a means of spread of this pest, however, cannot be considered as 
playing any unportant part in its wide dispersal. 
The inereasing density of pear, in areas where considerable infestation already 
exists, is due partly, of course, to the means already indicated, but chiefly to 
direct extension in size of the original plants and the breaking off of segments 
18 
