Gr. H. F. Nuttall 
199 
88 :100. There being numerous specimens in Lot B, the largest and 
smallest which could be found were measured ; the greater variation 
observed in Lot A is, therefore, all the more striking, and it is clearly 
attributable to the larvae having been removed from the host at 
different stages of engorgement. 
Variation in Adults. Figs. 3 and 4. 
We now come to the adults which emerged from the nymphs of 
Lots C, D, E and F respectively. (The signs L and 0 denote Larvae 
and Nymphs respectively.) 
In Lot C, picked as L and 0, the smallest 
<? measured 
1-8x1 
The largest 
1-8 x 1-1 
)> >> 5 ) ¥ 
In Lot D, picked as L but fully gorged as O’s, 
i 
1- 8x1 
2- 8 x 1-9 
2- 5 x l-o 
3- 8 x 2-o 
do. 
¥ 
2-9 x 1-8 
3-8 x 2-3 
In Lot E, gorged as L but picked as O’s, 
2-2 x 1-3 
4-3 x 3-8 
do. 
¥ 
2-0 x 1-3 
3-8 x 2-4 
In Lot F, normally fed as L and O’s, 
S 
3-0x 2-0 
4-4 x 2-8 
do. 
¥ 
3-5 x 2-2 
4-3 x 2-8 
The time occupied in feeding upon the host and in metamorphosis 
varied in individuals, and did not appear to be influenced by the picking- 
process during the previous stage. 
Out of 26 lots of R. appendiculatus collected in Africa off hosts, 
the smallest and largest </s were measured. The smallest f measured 
L9 mm. in length, the largest 4'4 ; a considerable variation is observable 
in ticks taken from the same host. It is clear, therefore, that we have 
reproduced, under experimental conditions, large and small forms of 
ticks comparable with those observed in nature. Our smallest male 
produced experimentally measured 1'8 inm. in length. There, never¬ 
theless, remains a considerable normal variation in size which has to be 
reckoned with ; in Lot F the males varied between 3 and 4 - 4 mm. in 
length. I may add that the small adults of Lot C, picked as L and O’s, 
were placed upon a host and behaved in a normal manner, the $s 
attaining almost a normal measurement when engorged (10 x 7 mm.) 
and laying eggs of normal size. The experiments are being continued 
and will be reported upon in a future paper. 
It should be noted that the smallest adults were obtained from 
individuals picked as larvae and nymphs (Lot C). They varied most 
in size when picked as nymphs but not as larvae (Lot E), ranging from 
very small forms to sizes within the normal range. When picked as L 
