N. CUNLIFFE AND 6. H. F. NlJTTALL 
347 
great variation in the extent of engorgement at each stage, but this is not 
correlated with the ecdysis period. The largest meal may be taken either 
before or after an individual reaches maturity. 
6. Moisture has an adverse influence on the vitality of the individual, 
excess of moisture inhibiting growth. 
7. An approximation to the stage of development attained can be made 
after the study of the structure of the hypostome, leg and spiracle. The 
larval and first four nymphal stages are fairly well differentiated, much more 
so than the later stages, but variation due to nutrition requires further study. 
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Cunliffe, N. (1913). Rhipicephalus sanguineus. Variation in size and structure due to 
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137-142. 
Nuttall, G. H. F. (1911, a). On the adaptation of ticks to the habits of their hosts. 
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