36 THE SCOTTISH NATURALIST 



other organs ; but the number of living bacteria to be found 

 in these organs is invariably small. To some degree they 

 are no doubt harmful ; but no evidence was obtained that 

 the death of the host could ever be attributed to their direct 

 influence. On the other hand, the presence of eosinophilia 

 in the blood, as demonstrated by Dr Fantham, indicates that 

 certain substances secreted or excreted by the parasites pass 

 into the circulation ; and this fact, together with the loss of 

 function in the caeca owing to the extensive decortication 

 of the epithelial lining by the worms, sufficiently accounts 

 for the resulting symptoms of the disease, and for the heavy 

 mortality in the birds so affected. 



The Life-history of the strongyle worm [Trichostrongylus 

 pei'gracilis), an exceedingly fine hair-like worm of about one- 

 third of an inch in length, has been thoroughly worked out 

 by Dr Leiper, Helminthologist to the London School of 

 Tropical Medicine. The egg being laid within the host, 

 passes out, and the larvae hatch and undergo their early 

 metamorphoses on damp earth. Still aided by moisture, 

 the larvae afterwards wriggle up to the heather tips, are 

 there swallowed by a Grouse, complete their life-cycle, and 

 become sexually reproductive, all within a very few days. 

 Counteracting influences are sun, drought, and to some 

 extent frost. Owing probably to these influences, infection 

 is in reality almost confined to the spring months, and the 

 mortality greatest during the periods of pairing and nesting. 

 Outbreaks do not in fact occur in autumn, though owing to 

 the increased opportunities of collecting sick (but, in fact, 

 convalescent) birds at that season, the contrary has hitherto 

 been generally held. The only remedy is to be looked for in 

 the provision of a plentiful food supply. Grouse are heavy 

 feeders ; but only a small proportion of the heather on many 

 moors is suitable for their food. The larger the supply of 

 good, regularly burnt, feeding heather on a moor in propor- 

 tion to the stock on the ground, the greater will be the resist- 

 ing power of the birds, and the smaller also the proportion of 

 infected plants. " During the months of May, June, and July 

 the fresh young shoots of heather are probably more nourish- 

 ing than at any other time of the year. In July, August, and 



